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CHANGELOG
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1/**@page RN80 Release notes for SCIP 8.0
2
3@section RN805 SCIP 8.1.0
4*************************
5
6Fixed bugs
7----------
8
9- fixed that scaling of rows in Gurobi interface (SCIPlpiScaleRow()) changed infinite sides to large finite ones (1e20) when scale factor is negative
10- check whether objective limit is truly reached in SCIPlpiIsStable()
11- if an objective limit is set and Mosek claims that it is exceeded, check that this is indeed the case in SCIPlpiIsStable()
12- the .mps file reader was extended to additionally accept .mps files with the objective sense section on one line
13- ensure that delayed cutpool separation does not happen if enough cuts have been found already
14- fixed that a Gurobi or Mosek interface (LPI) could not be freed from a thread different than the one it was created in, which lead to problems when, e.g., using the concurrent optimizer
15- in cons_varbound if both variables are fixed, instead of propagating the constraint check the feasibility of the constraint since propagating can lead to unnecessary numerical troubles
16- fixed memory leak in branching rule "distribution"
17- fixed that undercover did not enforce that sufficiently many variables in an and-constraints were fixed to have it linearized in the generated sub-scip
18- fixed two bugs in cons_varbound: avoid adding variable bounds if vbdcoef is infinite and unlock/lock variables if lhs/rhs/vbdcoef are changed
19- globalize constraint changes before bound changes during the effective root shift in treeSwitchPath() to correctly update variable locks by avoiding global bounds with outstanding bound change events when deleting constraints
20- fixed error when attempting to copy SCIP with activated pricers
21- remove integrality check for implicit integral variables in cons_integral.c, updated the definition for variable type implicit integer to be more explicit that these variables can take fractional values, and updated FAQ entry
22- updated and, or, and pseudoboolean constraint handlers to better handle fractional implicit integer variables in enforcement
23- avoid invalid strong Chvatal-Gomory cuts by ceiling with tolerance in the calculation of parameter k and flooring slack coefficients with standard epsilon tolerance as well as quad precision
24- add missing row links to columns in SCIPflushRowExtensions() required to maintain correct row norms
25- restrict separator intobj to solutions for which there can be no better feasible integral objective values to avoid cutting them off
26- delay removal of clique lists from SCIPvarRemoveCliquesImplicsVbs() into cliqueCleanup() to avoid segmentation faults by incomplete cleanups after variable conversions
27- reject sub-solutions with invalid objectives in SCIPtranslateSubSols() due to contradicting infinite contributions
28- correct column index in getMinMaxActivityResiduals() to make presolver dualinfer work
29- copy quiet flag from main scip's message handler to the one of solverscip in concurrent optimization
30- avoid bound tightening cycles towards huge redundancy bounds in fullDualPresolve() to avert fatal numerical trouble in representing vertices of linear relaxations with unbounded domains
31- fix problem where debug solution did not work if branching constraints are present
32- update index of dominating variable on coefficient deletion in dualPresolving() of constraint handler logicor
33- pass on flags from a redundant to the implying varbound constraint in preprocessConstraintPairs() to avoid suboptimal fixings by model relaxations
34- apply reductions of dualinfer only if a dual solution exists (primal is bounded)
35- before presolving is finished check solutions before retransforming them including tiny values to keep check flags consistent
36- disable heuristics before and during presolving in benders decomposition to avoid messing up the objective structure in the solution store by dropping auxiliary variables in the required retransformations
37- correct local flag of singleton conflict constraints in tightenSingleVar() against invalid bound globalization
38- respect unboundedness in the computation of activity bounds in conflict.c to avoid invalid huge bounds due to small coefficients on unbounded variables
39- ensure positive sides of a linear constraint when recognizing a set partition in rangedRowSimplify() to account for redundancy issues
40- relax numerical conditions for variable aggregations to avert invalid variable fixings
41- fixed harmless read of uninitialized data when creating parameters
42
43Performance improvements
44------------------------
45
46- Use sassy/bliss as default symmetry computation package.
47
48Interface changes
49-----------------
50
51### Interfaces to external software
52
53- added interface to nauty/traces for symmetry computation
54- added interface to sassy, a preprocessor for symmetry computation
55- The directory src/sassy contains the source code of sassy.
56
57Build system
58------------
59
60### Cmake
61
62- added flag option "SYM=sbliss" for using sassy/bliss as a graph automorphism package
63
64### Makefile
65
66- added flag option "nauty" for SYM variable to specify which graph automorphism package should be used
67- added flag option "sbliss" for SYM variable to specify which graph automorphism package should be used
68- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP
69
70Miscellaneous
71-------------
72
73- the parameter change callback is no longer called at the moment a parameter is created
74
75@section RN804 SCIP 8.0.4
76*************************
77
78Features
79--------
80
81- use quad precision in cutsSubstituteMIR() for substituting slack variables into CMIR cuts
82- use quad precision for activity computations in cons_linear.c
83
84### Deleted and changed API methods
85
86- SCIPshrinkDisjunctiveVarSet() no longer attempts to cutoff the current node if it finds the
87 given disjunction to be infeasible; it is now in the responsibility of the caller to act accordingly
88
89### New API functions
90
91- added SCIPskipSpace
92- added XML parser routines from src/xml/xml.h
93
94### Interfaces to external software
95
96- updated XPRESS interface to work with XPRESS 41 as well
97
98### Changed parameters
99
100- changed integer parameter "propagating/symmetry/recomputrestart" from range {0, 1, 2} to being fixed at value 0
101
102Unit tests
103----------
104
105- added new checks for objective, bounds and sides inside the scaling tests in lpi/change.c
106
107Fixed bugs
108----------
109
110- relax condition of assert in lpSolve to hold only if lp/checkstability is true
111- OPB reader: dynamically increase the size of the line buffer for reading in getMaxAndConsDim()
112- Enabled the solution limit checks in SCIPsolveIsStopped in solve.c when in SCIP_STAGE_PRESOLVING
113- fix quad precision comparison for the calculation of knapsackcover constraints.
114- force copying of symmetry constraints for concurrent solve
115- increase the precision of double multiplications in quad precision environments
116- corrected handling of different variable types in symmetry
117- orbitope detection: refine computation of overlap structure and fixed bug in finding orbitope generators
118- ensure that winner is always determined in concurrent mode
119- when a row with invalid index range is added to the global cutpool, update the indices instead of failing with an assert
120- update of watched literals in cons_xor.c and ensure that fixed variables are counted in propacateCons()
121- avoid some numerical issue in check for redundant variables in linear constraints (introduced with version 8.0.2)
122- more rows are treated as being integral in cutsSubstituteMIR() for CMIR cuts
123- fixed several relaxations of the rhs of cuts to 0 in cuts.c
124- avoid aggregation into a single linear constraint if they should not be upgraded (needed for indicator constraints)
125- apply effective root changes before fork is repropagated during treeSwitchPath() in tree.c
126- avoid invalid objective value for solutions generated from an unbounded LP relaxation in case of a nonlinear objective function
127- disable recomputing symmetries after a restart (constraint removal is not permitted)
128- avoid cutting off optimal solutions for small feasibility tolerances in conflict analysis
129- initialize variable in presol_dualsparsify.c
130- fix in presolving of variable bound constraints to use absolute instead of relative difference
131- free variable histories in reoptimization mode
132- handle whitespaces in interactive shell history consistently
133- check and enforce equalities on which the objective is projected in cons_linear.c
134- ensure row feasibilities of solution shiftings in heur_oneopt.c and heur_twoopt.c
135- remove rounded row check blocking tolerable primal solutions in cons_varbound.c
136- fixed that presolve of logicor-constraints may have attempted to cutoff a root of the not yet existing branch-and-bound tree
137- only consider positive slack variables as active in benders.c
138- in the feasibility check of and/or constraints, allow for fractional values in operands
139- fixed linear outer-approximation for some composite absolute-value expressions
140
141Miscellaneous
142-------------
143
144- Extended documentation of the parameter limits/solutions to point out that the limit is first checked in presolving
145- Added more information about using SCIPcache- and SCIPflushRowExtensions() to documentation and comments
146- Extended the `how to add' sections of the documentation by adding information on how to include default plugins into SCIP
147
148@section RN803 SCIP 8.0.3
149*************************
150
151Examples and applications
152-------------------------
153
154- Externalize STP and PolySCIP applications
155
156Interface changes
157-----------------
158
159### Command line interface
160
161- When running the AMPL interface, the .nl filename extension does not need to be omitted for the input file anymore.
162
163Build system
164------------
165
166### Cmake
167
168- Forbid CMAKE_BUILD_TYPE nonstandard values
169- Move -I/path/to/src/amplmp/include to front of compiler flags for include directories
170
171### Makefile
172
173Fixed bugs
174----------
175
176- fixed an incorrect handling of xor constraints
177- the feasibility checker for integrality constraints now uses checkintegrality even for implied integers
178- skip integrality check in cons_integral for relaxation-only implicit-integer variables
179- fixed an issue caused by aggregated variables not added to a hashmap in the xor constraint handler
180- changed function solveRowEchelonGF2 in cons_xor.c to avoid errors if rank is 0
181- fixed that the implication presolver tried to aggregate or tighten bounds of multiaggregated variables
182- fixed a sign check in detection of linear constraints that are parallel to the objective
183- fixed bug in Clp and lpi_clp with missing basis information when calling the barrier with crossover; needs new Clp version
184- do not assume aggregation is successful in cons_setppc.c
185
186Miscellaneous
187-------------
188
189- Changed license to Apache 2.0, see https://www.apache.org/licenses/LICENSE-2.0.
190- When an LP could not be solved accurately, scaling is now turned off as a last fall-back method.
191- Methods for using the debug solution mechanism SCIPdebugAddSolVal, SCIPdebugGetSol, SCIPdebugGetSolVal,
192 SCIPdebugSolIsValidInSubtree, SCIPdebugIsMainscip, SCIPdebugSolEnable, SCIPdebugSolDisable, SCIPdebugSolIsEnabled,
193 SCIPwithDebugSol are now exported
194
195Known bugs
196----------
197
198@section RN802 SCIP 8.0.2
199*************************
200
201Interface changes
202-----------------
203
204### Deleted and changed API methods
205
206- added input parameter SCIP_Bool initiallp to SCIPcutselsSelect
207- changed function type int to SCIP_Longint for SCIPcutpoolGetMaxNCuts
208- replaced SCIPsepastoreGetNCutsFound with SCIPsepastoreGetNCutsAdded following the naming convention for the new statistics
209- replaced SCIPsepaIncNAppliedCuts with SCIPsepaIncNCutsApplied
210
211### New API functions
212
213- added SCIPsepastoreGetNCutsAdded, SCIPsepastoreGetNCutsAddedViaPool, SCIPsepastoreGetNCutsAddedDirect
214- added SCIPsepaIncNCutsAdded, SCIPsepaDecNCutsAdded, SCIPsepaIncNCutsApplied, SCIPsepaGetNRootCalls, SCIPsepaGetNCutsAdded, SCIPsepaGetNCutsAddedViaPool, SCIPsepaGetNCutsAddedDirect, SCIPsepaGetNCutsAppliedViaPool, SCIPsepaGetNCutsAppliedDirect
215- added SCIPcutpoolGetNRootCalls, SCIPcutpoolGetNCutsAdded, SCIPcutpoolAddMaxNCuts, SCIPcutpoolSetTime, SCIPcutpoolAddNCalls, SCIPcutpoolAddNRootCalls, SCIPcutpoolAddNCutsFound, SCIPcutpoolAddNCutsAdded,
216- added SCIPcutselGetNCalls, SCIPcutselGetNRootCalls, SCIPcutselGetNRootCuts, SCIPcutselGetNRootForcedCuts, SCIPcutselGetNRootCutsFiltered, SCIPcutselGetNLocalCuts, SCIPcutselGetNLocalForcedCuts, SCIPcutselGetNLocalCutsFiltered,
217
218### Interfaces to external software
219
220- Added compatibility with Mosek 10.0.18.
221
222### New parameters
223
224- new parameters to turn on more statistics: misc/showdivingstats (diving heuristics), heuristics/alns/shownbstats (ALNS), estimation/showstats (tree size estimation)
225
226### Data structures
227
228- added nrootcalls and ncutsadded to SCIP_Cutpool
229- added fromcutpool flag to SCIP_Row and fixed 33 bit allocation
230- added ncalls, nrootcalls, nrootcutsselected, nrootcutsforced, nrootcutsfiltered, nlocalcutsselected, nlocalcutsforced, nlocalcutsfiltered to SCIP_Cutsel
231- added ncutsadded, ncutsaddedviapool, ncutsaddeddirect, ncutsappliedviapool, ncutsapplieddirect, nrootcalls to SCIP_Sepa
232- added ncutsadded, ncutsaddedviapool, ncutsaddeddirect to SCIP_Sepastore
233- fixed statistics of relaxators w.r.t. number of times conss/cuts were added
234
235Build system
236------------
237
238### Cmake
239
240- new option `-DAUTOBUILD` that configures scip with dependencies on availability.
241 Packages like Ipopt, PaPILO, Readline, Zimpl, ZLIB, GMP, Worhp are automatically found and linked, otherwise ignored.
242 The individual flags for these packages are ignored. This makes a quick build easier. It is by default set to off.
243
244Fixed bugs
245----------
246
247- read objective offset from ZIMPL files
248- Make sure that objective limit is disabled if not all variables are in the LP. If we would run into
249 an objective limit in this case, the results of the LP solver are unclear.
250- fixed bug in reopt.c, which occured for bounds outside of current valid bounds
251- fixed problem with recomputing symmetries after a restart
252- fixed bug in SCIPcalcMIR() with wrong order of arguments for removeZerosQuad()
253- fixed segmentation fault in update of cut statistic
254- fixed bug in presolving of and constraints by merging variables with multiple occurrences before cliquePresolve()
255- fixed bug in dual presolving of linear constraints by setting implicit integers to integers in multi-aggregation
256- fixed update of presolve statistics on added constraints and changed coefficients in constraint handler for nonlinear constraints
257- fixed bug with reading CIP files with large constraints split over several lines
258- fixed bug with infinite bounds in the computation of conflict cuts
259- fixed check for unbounded solution constructed by SCIPlpGetUnboundedSol(): The constructed solution is very likely infeasible
260 since scaling increases small numerical feasibility violations. Therefore, the solution is now always accepted. However, the
261 feasibility of the ray is now checked. This fix now might lead to several rounds of separation in order to resolve unbounded solutions,
262 whereas previously SCIP started to branch immediately.
263- changed to absolute tolerances in all redundancy checks for linear constraints
264
265Miscellaneous
266-------------
267
268- Added extended cutselector statistics splitting between root node specific and general statistics
269- Added extended and refined cutpool statistics showing the number of cuts added from the cutpool to the sepastore
270- Added extended and refined separator statistics to get a better view of the individual generators performance
271- turned off output of statistics for the following information by default:
272 diving heuristics, ALNS neighborhood information and tree size estimation statistics;
273 they can be turned on using the following new parameters:
274 misc/showdivingstats (diving heuristics), heuristics/alns/shownbstats (ALNS), estimation/showstats (tree size estimation)
275
276@section RN801 SCIP 8.0.1
277*************************
278Features
279--------
280
281- clique lifting in cons_setppc (parameter enablecliquelifting) is only disabled if it has been applied
282- avoid warning if Mosek has reached/exceeded the objective limit
283- improved curvature check for quadratic expressions when extended formulations are disabled
284
285Examples and applications
286-------------------------
287
288- Fixed handling of enforcing in the TSP example.
289
290Interface changes
291-----------------
292
293### Interfaces to external software
294
295- Added compatibility with Mosek 10.0.13.
296
297Build system
298------------
299
300- BLISS is now built from the vendored version from https://github.com/ds4dm/Bliss
301
302### Cmake
303
304- avoid warnings about unrecognized compiler warning silencing options when compilation with GCC fails
305- adjust mosek find module to version 9.3
306- added cmake compatibility for ipopt versions 3.14.x
307
308### Makefile
309
310- avoid warnings about unrecognized compiler warning silencing options when compilation with GCC fails
311- fixed that compilation with MS/Intel compilers on Windows and Cray compilers was broken when enabling PAPILO
312
313Fixed bugs
314----------
315
316- fixed uninitialized array in detection of suborbitopes
317- Fixed problem with reading long lines in LP/FZN/OPB/Diff-files. The buffer is now reallocated,
318 which also should be much faster.
319- fixed that recursive products in expressions were sometimes not flattened
320- fixed that expressions in original variables could not be simplified
321- fixed handling of objective limit with Mosek
322- made SCIPlpiGetSolverName()/SCIPlpiGetSolverDesc() thread-safe for LP Solvers (Cplex,Gurobi,Glop,Mosek,SoPlex,Xpress)
323- made SYMsymmetryGetName() thread-safe for Bliss
324- fixed memory allocation issue in detection of SOC nlhdlr
325- fixed that reaching the walltime limit in Ipopt was not handled properly
326- Deactivated dual fixing of unlocked variables with zero objective in presol_milp that SCIP is unable to postsolve.
327- set the column flag kImplInt for implicit integers in the papilo problem
328- fixed bug in propagation of indicator constraints (one case always reported a change through propagation)
329
330@section RN800 SCIP 8.0.0
331*************************
332
333Features
334--------
335
336- Variables that were marked as relaxation-only and that were not used in any solution (SCIP_SOL)
337 are now deleted when during a restart.
338- New symmetry handling method, symmetry handling inequalities based on the Schreier Sims table,
339 which is able to handle symmetries of arbitrary kinds of variables.
340- Revise way in which external memory (e.g., of LP-solver) is estimated.
341- The symmetry code can now heuristically search for orbitopes that do not completely handle
342 a symmetry component and add certain Schreier Sims cuts to such components.
343- The LPIs for Gurobi and Mosek are thread-safe now.
344- The complete code is now thread-safe by default.
345- New separator to generate mixing cuts (works well for stochastic programming with probabilistic constraint).
346- New parsing routines for cons_orbisack and cons_symresack.
347- Variables can now be marked to forbid aggregation.
348- Heuristic PADM can now reoptimize found solution with original objective function.
349- Added code to support debugging of catching or releasing of variables to var.c (prints backtrace
350 when catching and releasing).
351- SCIPintervalSin() and SCIPintervalCos() are now rounding-safe.
352- Removed special handling of second-order cones in undercover heuristic for now.
353- Removed use of Hessian sparsity pattern for nonquadratic nonlinear constraints in undercover heuristic.
354- Added reader for AMPL .nl files.
355- New separator sepa_rlt to compute cuts via the reformulation-linearization technique (RLT).
356- New separator sepa_minor to compute cuts from 2x2 minors of a violated semidefiniteness constraint that is
357 implied by the extended formulation for bilinear products.
358- New separator sepa_interminor to compute intersection cuts from 2x2 (not only principle) minors of a violated
359 rank-one constraint that is implied by the extended formulation for bilinear products.
360- Symmetry handling has been extended to detect also symmetries between variables that also appear in nonlinear constraints.
361- Improved OBBT propagator by only considering variables that are contained in at least one nonconvex expression that has an auxiliary variable.
362- Default parameter settings for NLP solves are now defined independently of the NLP solver.
363- Added table to print statistics on NLP solvers.
364- Knapsack, linear, logicor, setppc, and varbound constraints now add themselves to the NLP relaxation, if enabled.
365 And, linking constraints and bounddisjunctions in one variable are added to the NLP relaxation now.
366- Ipopt interface now supports warmstarts from a full primal/dual solution pair.
367- Extended data structure SCIP_ROWPREP and routines to assemble a linear inequality before it is turned into a SCIP row and
368 made it available via the API.
369- MIR procedure is now available for strengthening the Benders' optimality cut
370- SCIPbranchcandCalcLPCands() now also returns fractional variables in unbounded solutions.
371- New emphasis "benchmark" to avoid different solving paths that may come from checking remaining memory.
372- New plugin type for cut selection: users can now include their own cut selection rules, default rule moved to cutsel_hybrid.
373- New construction heuristic DPS which additionally needs a user-provided decomposition and splits the problem into several sub-SCIPs
374 according to this decomposition. The sub-SCIPs are solved and updated repeatedly until a feasible solution of the original problem is found.
375
376Expressions:
377- Removed support for expression types min and max for now. Removed support for expression type sign.
378 Removed complex expression types sum, product, linear, quadratic, polynomial.
379 Removed support for parameterized expressions.
380- Added support for expression types sin, cos, and entropy. Added an expression type that stores a SCIP variable.
381- Added handling of sin and cos expressions in OSiL reader.
382- Added handling of sin, cos, and tan expressions in ZIMPL reader.
383- Added expression handler plugin type, removed user expression type.
384- Replaced expressions, expression trees, and expression graphs by a new implementation of expressions.
385- Added differentiation methods (Gradients and Hessian directions) to expressions.
386- Added integrality information to expressions.
387- Added comparison and hashing of expressions.
388- Improved simplification of expressions and identification of common subexpressions, in particular terms that appear
389 equally in several quadratic functions are now identified.
390- Expression simplification now expands powers also when the resulting exponents will be larger than 2.
391- Added table to print statistics on expression handlers.
392- Removed interval-arithmetic evaluation from expression interpreter (interfaces to automatic differentiation codes).
393- Hessians for user-provided expression handlers are not available in the NLP solver interfaces for now.
394- Sparse Hessians are now returned by expression interpreter. Removed dense Hessians.
395
396Constraint handlers for NLP:
397- cons_nonlinear has been completely rewritten and now handles constraints of the form lhs <= expr <= rhs, where
398 expr is an expression using the new expression type. A linear part of a nonlinear constraint is no longer distinguished.
399- Methods that work on a particular nonlinear structure are now implemented via nonlinear handlers (nlhdlr).
400 These handlers are plugins of cons_nonlinear and interact with cons_nonlinear by detecting structures in expressions and
401 providing propagation and separation mechanisms.
402- Added nlhdlr "default" as a mandatory nlhdlr: this is a nlhdlr that gets active on expressions that no other nlhdlr handles.
403 It then uses the callbacks implemented in expression handlers to provide domain propagation and linear under/overestimates.
404- Added nlhdlr for quadratic expressions: domain propagation that was previously part of cons_quadratic; separation via intersection cuts (currently disabled).
405- Added nlhdlr for bilinear expressions: collects bilinear products and provides under/overestimation of a product over a 2D-projection of the LP.
406- Added nlhdlr for convex and concave expressions: detection of convex/concave subexpressions and linear under/overestimation.
407- Added nlhdlr for quotients: detects quotients, provides specialized linear under/overestimation and domain propagation for univariate quotients.
408- Added nlhdlr for perspective reformulations: detects expressions in semi-continuous variables and tightens linear
409 under/overestimates of these expressions by applying a perspective transformation.
410- Added nlhdlr for second-order cones: detects second-order cone constraints (as ||x|| <= t or a quadratic that can written like that) and
411 separates on a disaggregated reformulation (similar to cons_soc previously).
412- Removed constraint handlers abspower, bivariate, quadratic, and soc.
413- Removed simplification of duplicate abspower constraints for now.
414 Removed simplification of abspower constraints with loose variables.
415 Removed resolving of domain propagation (ConsResProp callback) and conflict analysis for abspower constraints.
416 Removed propagation of varbounds for variables of abspower constraints.
417 Removed reformulation of abs(x)^p * x into signpower expression for now.
418- Removed reformulation of SOC constraints when adding to the NLP.
419 Removed possibility to add linearizations a la Glineur or BenTal&Nemirovski for SOC constraints.
420- Removed possibility to disaggregate quadratic constraints.
421 Removed lifted tangent inequalities for bilinear terms in quadratic constraints.
422 Removed option to project LP solution onto feasible region of a quadratic constraint via interior point or gauge function.
423 Removed handling of unbounded LPs when enforcing quadratic constraints.
424- Removed construction of cuts from interval gradients for nonlinear constraints.
425 Removed possibility to pretend that all nonlinear constraints are convex.
426 Removed possibility to create local or non-initial nonlinear constraints for now.
427- Removed explicit reformulation of nonlinear constraints in presolve.
428 An extended formulation is now generated implicitly and used to construct the LP relaxation,
429 but the original formulation is used to check feasibility, propagate variable domains, etc.
430 Variables that are added for the extended formulation are now marked as relaxation-only.
431- Improved locking of nonlinear variables in nonlinear constraints by taking monotonicity into account.
432- Improved mechanisms to detect and handle structures in nonlinear constraints, which allows for several algorithms
433 to work simultaneously on equal or overlapping expressions.
434- Improved linearization of (sums of) products of binary variables, e.g., clique information is now taken into account.
435 Removed option to linearize products between a binary and a non-binary variable.
436- Nonlinear constraints with the same function (but possibly different left- or right-hand-side) are now merged.
437- When a variable appears in only one concave less-or-equal constraint, it will be fixed to one of its bounds in more cases now.
438- New branching rule for variables in nonlinear constraints (implemented in cons_nonlinear) that scores candidates
439 based on constraint violation, variable type, and pseudo-costs simultaneously.
440- Added tables to print statistics of nonlinear constraint handler and nonlinear handlers.
441
442Performance improvements
443------------------------
444
445- Use the objective cutoff row as base row for separation in sepa_aggregation.c.
446- Separate lifted cover cuts based on newer lifting function of Letchford and Souli (2019) in sepa_aggregation.c.
447- In-tree restarts due to tree size estimation have been made compatible with orbital fixing.
448- Improved upgrade of orbisacks to packing/partitioning orbitopes.
449- Improved running time of symresack cover separation.
450- Improved propagation algorithm for orbisack and symresack.
451- Improved handling for expressions of type signpower in CppAD interface by making use of CppADs conditional expressions.
452- Faster reevaluation of Hessian for quadratic expressions in CppAD interface.
453- Enabled optimization of taped expressions in the CppAD interface.
454- Sparse Hessian evaluation for expressions with sparse Hessian in the CppAD interface.
455- Disabled branching on variables that are added for the extended formulation of a nonlinear constraint.
456- Prefer branching on variables in nonconvex terms of nonlinear constraints also if a cut could be generated but would yield a small reduction in the convexification gap only.
457- When violations of nonlinear constraints are tiny, the feasibility tolerance for the LP relaxation may now be reduced temporarily to allow for cuts to have an effect.
458- Improved under/overestimation of multidimensional vertex-polyhedral (e.g., multilinear or concave) functions by use of scaling and keeping the cut-generating LP around.
459- Products in nonlinear constraints are no longer disaggregated for the extended formulation.
460- No longer relax bounds of integral variables when computing bounds on activity in nonlinear constraints.
461- Revised and improved Ipopt interface.
462- Revised and improved subNLP primal heuristic, in particular choice of iteration limit and starting condition and reuse of subSCIP.
463- Merge strongcg into the gomory separator to avoid computing the same base equality twice. The files
464 sepa_strongcg.{h|c} have been removed.
465- The RENS neighborhood in ALNS now fixes fractional variables if necessary for reaching its target fixing rate.
466- Use cpsolver emphasis in sepa_rapidlearning.
467- If decomposition/maxgraphedge = 0, the computation of the block graph is completely turned off.
468- Fixed a performance bug in cons_integral.c where rounding information was passed incorrectly to the generic diving algorithm.
469
470Examples and applications
471-------------------------
472
473- Add c++ Sudoku example
474- Removed circle.c and renamed string.c to spring.c in CallableLibrary example.
475- SCIP-Jack (Steiner tree application):
476 Most files have been modified and many new ones have been added (code base more than doubled).
477 Two new problem classes are supported: maximum-weight connected subgraph problem with budget constraints, partial-terminal node-weighted Steiner tree problem.
478 Major performance improvements accross all problem classes that are supported.
479
480Interface changes
481-----------------
482
483### New and changed callbacks
484
485- extend SEPAEXEC{LP,SOL} callbacks by parameter "depth", which should be used within separation instead of SCIPgetCurrentDepth()
486- extend SCIPseparateSolCutpool() by parameter "pretendroot", which is passed to SCIPcutpoolSeparate() instead of SCIPtreeGetCurrentDepth(scip->tree) == 0
487- removed SCIP_DECL_EXPRGRAPHVARADDED, SCIP_DECL_EXPRGRAPHVARREMOVE, SCIP_DECL_EXPRGRAPHVARCHGIDX
488- removed SCIP_DECL_USEREXPRESTIMATE, SCIP_DECL_USEREXPREVAL, SCIP_DECL_USEREXPRINTEVAL, SCIP_DECL_USEREXPRCURV, SCIP_DECL_USEREXPRPROP, SCIP_DECL_USEREXPRCOPYDATA, SCIP_DECL_USEREXPRFREEDATA, SCIP_DECL_USEREXPRPRINT
489- added SCIP_DECL_EXPR_OWNERFREE, SCIP_DECL_EXPR_OWNERPRINT, SCIP_DECL_EXPR_OWNEREVALACTIVITY, SCIP_DECL_EXPR_OWNERCREATE
490- added SCIP_DECL_EXPR_INTEVALVAR, SCIP_DECL_EXPR_MAPEXPR
491- added SCIP_DECL_EXPRCOPYHDLR, SCIP_DECL_EXPRFREEHDLR, SCIP_DECL_EXPRCOPYDATA, SCIP_DECL_EXPRFREEDATA, SCIP_DECL_EXPRPRINT, SCIP_DECL_EXPRPARSE, SCIP_DECL_EXPRCURVATURE, SCIP_DECL_EXPRMONOTONICITY, SCIP_DECL_EXPRINTEGRALITY, SCIP_DECL_EXPRHASH, SCIP_DECL_EXPRCOMPARE, SCIP_DECL_EXPREVAL, SCIP_DECL_EXPRBWDIFF, SCIP_DECL_EXPRFWDIFF, SCIP_DECL_EXPRBWFWDIFF, SCIP_DECL_EXPRINTEVAL, SCIP_DECL_EXPRESTIMATE, SCIP_DECL_EXPRINITESTIMATES, SCIP_DECL_EXPRSIMPLIFY, SCIP_DECL_EXPRREVERSEPROP
492- removed SCIP_DECL_QUADCONSUPGD
493- added SCIP_DECL_VERTEXPOLYFUN
494- added argument nvarexprs to SCIP_DECL_NONLINCONSUPGD to inform upgrade method about number of variables in constraint
495- removed SCIP_DECL_EXPRGRAPHNODEREFORM
496- added SCIP_DECL_NLHDLRCOPYHDLR, SCIP_DECL_NLHDLRFREEHDLRDATA, SCIP_DECL_NLHDLRFREEEXPRDATA, SCIP_DECL_NLHDLRINIT, SCIP_DECL_NLHDLREXIT, SCIP_DECL_NLHDLRDETECT, SCIP_DECL_NLHDLREVALAUX, SCIP_DECL_NLHDLRINTEVAL, SCIP_DECL_NLHDLRREVERSEPROP, SCIP_DECL_NLHDLRINITSEPA, SCIP_DECL_NLHDLREXITSEPA, SCIP_DECL_NLHDLRENFO, SCIP_DECL_NLHDLRESTIMATE
497- replaced BMS_BLKMEM* blkmem argument of SCIP_DECL_NLPICOPY by SCIP* scip, removed targetnlpi argument
498- added SCIP* scip and SCIP_NLPIDATA** nlpidata arguments to SCIP_DECL_NLPIFREE
499- added SCIP* scip to SCIP_DECL_NLPIGETSOLVERPOINTER, SCIP_DECL_NLPICREATEPROBLEM, SCIP_DECL_NLPIFREEPROBLEM, SCIP_DECL_NLPIGETPROBLEMPOINTER, SCIP_DECL_NLPIADDVARS, SCIP_DECL_NLPIADDCONSTRAINTS, SCIP_DECL_NLPISETOBJECTIVE, SCIP_DECL_NLPICHGVARBOUNDS, SCIP_DECL_NLPICHGCONSSIDES, SCIP_DECL_NLPIDELVARSET, SCIP_DECL_NLPIDELCONSSET, SCIP_DECL_NLPICHGLINEARCOEFS, SCIP_DECL_NLPICHGOBJCONSTANT, SCIP_DECL_NLPISETINITIALGUESS, SCIP_DECL_NLPISOLVE, SCIP_DECL_NLPIGETSOLSTAT, SCIP_DECL_NLPIGETTERMSTAT, SCIP_DECL_NLPIGETSOLUTION, SCIP_DECL_NLPIGETSTATISTICS
500- replaced SCIP_DECL_NLPICHGEXPRTREE by SCIP_DECL_NLPICHGEXPR
501- removed nquadelems, quadelems, exprvaridxs arguments from SCIP_DECL_NLPIADDCONSTRAINTS, changed exprtrees argument to exprs
502- removed nquadelems, quadelems, exprvaridxs arguments from SCIP_DECL_NLPISETOBJECTIVE, changed exprtree argument to expr
503- removed SCIP_DECL_NLPICHGQUADCOEFS, SCIP_DECL_NLPICHGNONLINCOEF, SCIP_DECL_NLPISETMESSAGEHDLR
504- added SCIP_NLPIPROBLEM* problem to SCIP_DECL_NLPIGETSOLVERPOINTER
505
506### Deleted and changed API methods
507
508- When calling SCIPdelVar() in the SCIP_STAGE_PROBLEM stage, it is now documented as the user's responsibility to ensure
509 the variable is not present in any constraints. Otherwise, SCIPsolve() now returns SCIP_INVALIDDATA.
510- removed SCIPselectCuts(), replaced by SCIPselectCutsHybrid() of the hybrid cut selector plugin
511- If SCIPvarMarkRelaxationOnly() is called for a variable, then this now need to happen before the
512 variable is added to the transformed problem (SCIPaddVar()).
513 SCIPvarMarkRelaxationOnly() will automatically call SCIPvarMarkDeletable().
514- SCIPcomputeOrbitsFilterSym() and SCIPcomputeComponentsSym(): Type of argument componentblocked
515 changed from SCIP_Shortbool* to unsigned*.
516- removed SCIPsetParam()
517- SCIPcreateConsOrbitope() and SCIPcreateConsBasicOrbitope() have two new arguments "usedynamicprop"
518 and "mayinteract" to encode whether a dynamic reordering of the orbitope rows shall be used in
519 full orbitope propagation and whether the orbitope might interact with other symmetry handling
520 methods, respectively.
521- internal function SCIPgetPropertiesPerm() has been replaced by SCIPisInvolutionPerm()
522- internal function SCIPgenerateOrbitopeVarsMatrix() has new arguments "storelexorder", "lexorder",
523 "nvarsorder", "maxnvarsorder" to compute and store the lexicographic order defined by an orbitope
524- renamed SCIPcomputeArraysIntersection() and SCIPcomputeArraysSetminus() to
525 SCIPcomputeArraysIntersectionInt() and SCIPcomputeArraysSetminusInt(), respectively, and changed
526 their return type from SCIP_RETCODE (which _always_ was SCIP_OKAY) to void
527- removed SCIPincludeDialogDefault(), use SCIPincludeDialogDefaultBasic() instead and check whether you also need SCIPincludeDialogDefaultSet() and SCIPincludeDialogDefaultFix()
528- removed exprint argument from SCIPaddNlRowGradientBenderscutOpt()
529- added copyexprhdlrs argument to SCIPcopyPlugins() (19th position)
530- added copycutselectors argument to SCIPcopyPlugins() (10th position)
531- removed refpoint argument from SCIPaddSquareSecant()
532- added argument exprdata to SYMcomputeSymmetryGenerators()
533- removed SCIPconsNonlinearGetRhs(), SCIPconsNonlinearGetLhs(), SCIPconsNonlinearAddLinearCoef()
534- removed arguments timelimit, minimprove, itercontingent, and iterused from SCIPapplyHeurSubNlp()
535- removed SCIPresolveSolHeurSubNlp(), SCIPgetSubScipHeurSubNlp(), SCIPgetVarMappingScip2SubScipHeurSubNlp(), SCIPgetVarMappingSubScip2ScipHeurSubNlp()
536- SCIPlockVarCons() and SCIPunlockVarCons() are now allowed in stage TRANSFORMED as well
537- Added functions SCIPsetSepaIsParentsepa(), SCIPsetSepaParentsepa() [in scip_sepa.h], SCIPsepaSetIsParentsepa(), SCIPsepaSetParentsepa() [in sepa.h],
538 SCIPsepaIsParentsepa(), SCIPsepaGetParentsepa() [in pub_sepa.h]
539- Added function SCIPpruneTree() to immediately delete nodes that were marked to be deleted with SCIPcutoffNode
540
541NLP:
542- SCIPhasNLPContinuousNonlinearity() now returns SCIP_RETCODE and has additional argument result
543- removed SCIPnlrowGetNQuadVars(), SCIPnlrowGetQuadVars(), SCIPnlrowSearchQuadVar(), SCIPnlrowGetNQuadElems(), SCIPnlrowGetQuadElems(), SCIPnlrowGetQuadData()
544- renamed SCIPnlrowGetExprtree() to SCIPnlrowGetExpr() and changed return type to SCIP_EXPR*
545- removed arguments nquadvars, quadvars, nquadelems, quadelems from SCIPcreateNlRow(); argument expr(ession) is now of type SCIP_EXPR*
546- removed SCIPaddQuadVarToNlRow(), SCIPaddQuadVarsToNlRow(), SCIPaddQuadElementToNlRow(), SCIPaddQuadElementsToNlRow(), SCIPchgNlRowQuadElement(), SCIPsetNlRowExprtreeParam(), SCIPsetNlRowExprtreeParams()
547- renamed SCIPsetNlRowExprtree() to SCIPsetNlRowExpr() and changed type of expr(tree) argument to SCIP_EXPR*
548- SCIPenableNLP() is no longer allowed in stages INITSOLVE and SOLVING
549- removed SCIPaddLinearConsToNlpHeurSubNlp()
550- SCIPhasNLPSolution() now returns true also if a infeasible solution to the NLP exists; SCIPcreateNLPSol() can now also be used when only an infeasible solution to the NLP exists
551- renamed SCIPsolveNLP() to SCIPsolveNLPParam() and added parameter SCIP_NLPPARAM param
552- removed SCIPsolveDiveNLP(), use SCIPsolveNLPParam() instead
553
554NLPI:
555- removed SCIPnlpiCopy(), SCIPnlpiFree(), SCIPnlpiChgQuadCoefs(), SCIPnlpiChgNonlinCoef(), SCIPnlpiSetMessageHdlr()
556- removed SCIPnlpiCreate() from public API, use SCIPincludeNlpi() instead
557- removed SCIPnlpiGetSolverPointer() from public API, use SCIPgetNlpiSolverPointer() instead
558- removed SCIPnlpiCreateProblem() from public API, use SCIPcreateNlpiProblem() instead
559- removed SCIPnlpiFreeProblem() from public API, use SCIPfreeNlpiProblem() instead
560- removed SCIPnlpiGetProblemPointer() from public API, use SCIPgetNlpiProblemPointer() instead
561- removed SCIPnlpiAddVars() from public API, use SCIPaddNlpiVars() instead
562- removed SCIPnlpiAddConstraints() from public API, use SCIPaddNlpiConstraints() instead
563- removed SCIPnlpiSetObjective() from public API, use SCIPsetNlpiObjective() instead
564- removed SCIPnlpiChgVarBounds() from public API, use SCIPchgNlpiVarBounds() instead
565- removed SCIPnlpiChgConsSides() from public API, use SCIPchgNlpiConsSides() instead
566- removed SCIPnlpiDelVarSet() from public API, use SCIPdelNlpiVarSet() instead
567- removed SCIPnlpiDelConsSet() from public API, use SCIPdelNlpiConsSet() instead
568- removed SCIPnlpiChgLinearCoefs() from public API, use SCIPchgNlpiLinearCoefs() instead
569- removed SCIPnlpiChgExprtree() from public API, use SCIPchgNlpiExpr() instead
570- removed SCIPnlpiChgObjConstant() from public API, use SCIPchgNlpiObjConstant() instead
571- removed SCIPnlpiSetInitialGuess() from public API, use SCIPsetNlpiInitialGuess() instead
572- removed SCIPnlpiSolve() from public API, use SCIPsolveNlpiParam() instead
573- removed SCIPnlpiGetSolstat() from public API, use SCIPgetNlpiSolstat() instead
574- removed SCIPnlpiGetTermstat() from public API, use SCIPgetNlpiTermstat() instead
575- removed SCIPnlpiGetSolution() from public API, use SCIPgetNlpiSolution() instead
576- removed SCIPnlpiGetStatistics() from public API, use SCIPgetNlpiStatistics() instead
577- removed SCIPnlpiGetWarmstartSize()
578- removed SCIPnlpiGetWarmstartMemo()
579- removed SCIPnlpiSetWarmstartMemo()
580- removed SCIPnlpiGetIntPar()
581- removed SCIPnlpiSetIntPar()
582- removed SCIPnlpiGetRealPar()
583- removed SCIPnlpiSetRealPar()
584- removed SCIPnlpiGetStringPar(),
585- removed SCIPnlpiSetStringPar()
586- removed SCIPnlpiSetPriority() from public API, use SCIPsetNlpiPriority() instead
587- removed argument nlpi from SCIPincludeNlpi() and added name, description, priority,
588 nlpicopy, nlpifree, nlpigetsolverpointer, nlpicreateproblem, nlpifreeproblem, nlpigetproblempointer, nlpiaddvars, nlpiaddconstraints, nlpisetobjective, nlpichgvarbounds, nlpichgconssides, nlpidelvarset, nlpidelconsset, nlpichglinearcoefs, nlpichgexpr, nlpichgobjconstant, nlpisetinitialguess, nlpisolve, nlpigetsolstat, nlpigettermstat, nlpigetsolution, nlpigetstatistics, nlpidata
589- removed SCIPcreateNlpSolverAll(), use SCIPincludeNlpSolverAll() instead
590- removed SCIPcreateNlpSolverFilterSQP(), use SCIPincludeNlpSolverFilterSQP() instead
591- removed SCIPcreateNlpSolverIpopt(), use SCIPincludeNlpSolverIpopt() instead
592- removed SCIPcreateNlpSolverWorhp(), use SCIPincludeNlpSolverWorhp() instead
593- replaced argument BMS_BLKMEM* blkmem of SCIPnlpiOracleCreate() by SCIP* scip
594- added argument SCIP* scip to SCIPnlpiOracleFree(), SCIPnlpiOracleSetProblemName(), SCIPnlpiOracleAddVars(), SCIPnlpiOracleAddConstraints(), SCIPnlpiOracleSetObjective(), SCIPnlpiOracleChgVarBounds(), SCIPnlpiOracleChgConsSides(), SCIPnlpiOracleDelVarSet(), SCIPnlpiOracleDelConsSet(), SCIPnlpiOracleChgLinearCoefs(), SCIPnlpiOracleChgObjConstant(), SCIPnlpiOracleGetEvalCapability(), SCIPnlpiOracleEvalObjectiveValue(), SCIPnlpiOracleEvalConstraintValue(), SCIPnlpiOracleEvalConstraintValues(), SCIPnlpiOracleEvalObjectiveGradient(), SCIPnlpiOracleEvalConstraintGradient(), SCIPnlpiOracleGetJacobianSparsity(), SCIPnlpiOracleEvalJacobian(), SCIPnlpiOracleGetHessianLagSparsity(), SCIPnlpiOracleEvalHessianLag(), SCIPnlpiOraclePrintProblem(), SCIPnlpiOraclePrintProblemGams()
595- removed arguments nquadelems, quadelems, exprvaridxs, exprtrees from SCIPnlpiOracleAddConstraints(), added argument SCIP_EXPR** exprs
596- removed arguments nquadelems, quadelems, exprvaridxs, exprtree from SCIPnlpiOracleSetObjective(), added argument SCIP_EXPR* expr
597- replaced arguments isnewx of SCIPnlpiOracleEvalHessianLag() by two arguments isnewx_obj and isnewx_cons
598- removed SCIPnlpiOracleChgExprtree(), use SCIPnlpiOracleChgExpr() instead
599- removed SCIPnlpiOracleSetInfinity(), SCIPnlpiOracleGetInfinity(), SCIPnlpiOracleChgQuadCoefs(), SCIPnlpiOracleChgExprParam(), SCIPnlpiOracleGetMaxDegree()
600- removed SCIPnlpiOracleGetVarDegree() and SCIPnlpiOracleGetVarDegrees(), use SCIPnlpiOracleIsVarNonlinear() and SCIPnlpiOracleGetVarCounts(), respectively, instead
601- removed SCIPnlpiOracleGetConstraintDegree(), use SCIPnlpiOracleIsConstraintNonlinear() instead
602- removed argument messagehdlr from SCIPnlpiOraclePrintProblem() and SCIPnlpiOraclePrintProblemGams()
603- removed SCIPcreateNlpiProb(), use SCIPcreateNlpiProblemFromNlRows() instead
604- renamed SCIPupdateNlpiProb() to SCIPupdateNlpiProblem() and moved into scip_nlpi.{h,c}
605- renamed SCIPaddNlpiProbRows() to SCIPaddNlpiProblemRows() and moved into scip_nlpi.{h,c}
606- removed SCIPsetModifiedDefaultSettingsIpopt()
607- removed SCIPgetIpoptApplicationPointerIpopt(), use SCIPgetNlpiSolverPointer() instead
608- removed SCIPnlpStatisticsCreate(), SCIPnlpStatisticsFree(), SCIPnlpStatisticsGetNIterations(), SCIPnlpStatisticsGetTotalTime(), SCIPnlpStatisticsSetNIterations(), SCIPnlpStatisticsSetTotalTime(), the struct is public now
609- renamed LapackDsyev() to SCIPcallLapackDsyevIpopt()
610- renamed SCIPsolveLinearProb() to SCIPsolveLinearEquationsIpopt()
611
612Expression interpreter:
613- removed functions that operated with SCIPInterval
614- changed first argument of SCIPexprintCreate() to SCIP*
615- added SCIP* as first argument to SCIPexprintFree()
616- added SCIP* as first argument to SCIPexprintCompile(), changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA**
617- added arguments SCIP*, SCIP_EXPRINT*, and SCIP_EXPR* as first arguments to SCIPexprintFreeData()
618- renamed SCIPexprintGetExprtreeCapability() to SCIPexprintGetExprCapability();
619 added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
620- removed SCIPexprintNewParametrization()
621- SCIPexprintEval(): added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
622- removed SCIPexprintEvalInt()
623- SCIPexprintGrad(): added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
624- removed SCIPexprintGradInt()
625- removed SCIPexprintHessianSparsityDense() and SCIPexprintHessianDense, use SCIPexprintHessianSparsity() and SCIPexprintHessian() instead
626
627Expressions:
628- removed SCIPexpropGetName(), use SCIPexprhdlrGetName() instead
629- removed SCIPexpropGetNChildren()
630- removed SCIPexprGetOperator(), use SCIPexprGetHdlr() instead
631- removed SCIPexprGetOpIndex(), SCIPexprGetOpReal(), SCIPexprGetOpData(), use SCIPexprGetData() instead
632- removed SCIPexprGetRealPowerExponent(), SCIPexprGetIntPowerExponent(), SCIPexprGetSignPowerExponent(), use SCIPgetExponentExprPow() instead
633- removed SCIPexprGetLinearCoefs(), SCIPexprGetLinearConstant(), use SCIPgetCoefsExprSum() and SCIPgetConstantExprSum() instead
634- removed SCIPexprGetQuadElements(), SCIPexprGetQuadConstant(), SCIPexprGetQuadLinearCoefs(), SCIPexprGetNQuadElements(), use SCIPexprGetQuadraticData(), SCIPexprGetQuadraticQuadTerm(), SCIPexprGetQuadraticBilinTerm() instead
635- removed SCIPexprGetMonomials(), SCIPexprGetNMonomials, SCIPexprGetPolynomialConstant(), SCIPexprGetMonomialCoef(), SCIPexprGetMonomialNFactors(), SCIPexprGetMonomialChildIndices(), SCIPexprGetMonomialExponents()
636- removed SCIPexprGetUserData(), SCIPexprHasUserEstimator(), SCIPexprGetUserEvalCapability()
637- removed SCIPexprCreate(), use SCIPcreateExpr() instead
638- removed SCIPexprCopyDeep(), use SCIPduplicateExpr() instead
639- removed SCIPexprFreeDeep(), use SCIPreleaseExpr() instead
640- removed SCIPexprFreeShallow()
641- removed SCIPexprAdd(), SCIPexprMulConstant()
642- removed SCIPexprCreateLinear(), use SCIPcreateExprSum() instead
643- replaced SCIPexprAddToLinear() by SCIPappendExprSumExpr()
644- replaced SCIPexprCreateQuadratic() by SCIPcreateExprQuadratic()
645- removed SCIPexprSortQuadElems()
646- removed SCIPexprCreatePolynomial(), SCIPexprAddMonomials(), SCIPexprChgPolynomialConstant(), SCIPexprMultiplyPolynomialByConstant(), SCIPexprMultiplyPolynomialByMonomial(), SCIPexprMultiplyPolynomialByPolynomial(), SCIPexprPolynomialPower()
647- removed SCIPexprMergeMonomials(), SCIPexprFreeMonomial(), SCIPexprSortMonomialFactors(), SCIPexprFindMonomialFactor(), SCIPexprAreMonomialsEqual(), SCIPexprAddMonomialFactors(), SCIPexprChgMonomialCoef(), SCIPexprMultiplyMonomialByMonomial(), SCIPexprMonomialPower(), SCIPexprMergeMonomialFactors(), SCIPexprSortMonomials()
648- replaced SCIPexprCreateMonomial() by SCIPcreateExprMonomial()
649- removed SCIPexprCreateUser(), use SCIPincludeExprhdlr() instead
650- removed SCIPexprHasParam(), SCIPexprGetMaxDegree(), SCIPexprGetVarsUsage()
651- replaced SCIPexprAreEqual() by SCIPcompareExpr()
652- replaced SCIPexprSimplify() by SCIPsimplifyExpr()
653- replaced SCIPexprEvalShallow() by SCIPcallExprEval()
654- replaced SCIPexprEval() by SCIPevalExpr()
655- replaced SCIPexprEvalIntShallow() by SCIPcallExprInteval()
656- replaced SCIPexprEvalInt() by SCIPevalExprActivity()
657- removed SCIPexprEvalUser(), SCIPexprEvalIntUser(), SCIPexprEstimateUser()
658- replaced SCIPexprCheckCurvature() by SCIPcomputeExprCurvature()
659- removed SCIPexprSubstituteVars(), use SCIPcopyExpr() instead
660- removed SCIPexprReindexVars(), SCIPexprReindexParams()
661- replaced SCIPexprPrint() by SCIPprintExpr()
662- replaced SCIPexprParse() by SCIPparseExpr()
663
664Expression tree:
665- removed SCIPexprtreeGetVars(), SCIPexprtreeSetVars(), SCIPexprtreeAddVars(), SCIPexprtreePrintWithNames(), SCIPexprtreeFindVar()
666- removed SCIPexprtreeGetRoot(), SCIPexprtreeGetNVars(), SCIPexprtreeGetNParams(), SCIPexprtreeGetParamVals(), SCIPexprtreeSetParamVal(), SCIPexprtreeHasParam()
667- removed SCIPexprtreeGetInterpreterData(), SCIPexprtreeSetInterpreterData(), SCIPexprtreeFreeInterpreterData()
668- removed SCIPexprtreeGetMaxDegree()
669- removed SCIPexprtreeEval(), use SCIPevalExpr() instead
670- removed SCIPexprtreeEvalInt(), use SCIPevalExprActivity() instead
671- removed SCIPexprtreePrint(), use SCIPprintExpr() instead
672- removed SCIPexprtreeCreate()
673- removed SCIPexprtreeCopy(), use SCIPduplicateExpr() instead
674- removed SCIPexprtreeFree(), use SCIPreleaseExpr() instead
675- removed SCIPexprtreeSetParams(), SCIPexprtreeGetVarsUsage()
676- removed SCIPexprtreeSimplify(), use SCIPsimplifyExpr() instead
677- removed SCIPexprtreeAddExpr()
678- removed SCIPexprtreeCheckCurvature(), use SCIPcomputeExprCurvature() instead
679- removed SCIPexprtreeSubstituteVars(), use SCIPcopyExpr() instead
680- removed SCIPquadelemSort(), SCIPquadelemSortedFind(), SCIPquadelemSqueeze()
681
682Expression graph:
683- removed SCIPexprgraphCaptureNode(), use SCIPcaptureExpr() instead
684- removed SCIPexprgraphIsNodeEnabled()
685- removed SCIPexprgraphGetNodeNChildren(), use SCIPexprGetNChildren() instead
686- removed SCIPexprgraphGetNodeChildren(), use SCIPexprGetChildren() instead
687- removed SCIPexprgraphGetNodeNParents(), SCIPexprgraphGetNodeParents(), SCIPexprgraphGetNodeDepth(), SCIPexprgraphGetNodePosition()
688- removed SCIPexprgraphGetNodeOperator(), use SCIPexprGetHdlr() instead
689- removed SCIPexprgraphGetNodeOperatorIndex(), SCIPexprgraphGetNodeOperatorReal(), use SCIPexprGetData() instead
690- removed SCIPexprgraphGetNodeVar(), use SCIPgetVarExprVar() instead
691- removed SCIPexprgraphGetNodeRealPowerExponent(), SCIPexprgraphGetNodeIntPowerExponent(), SCIPexprgraphGetNodeSignPowerExponent(), use SCIPgetExponentExprPow() instead
692- removed SCIPexprgraphGetNodeLinearCoefs(), SCIPexprgraphGetNodeLinearConstant(), use SCIPgetCoefsExprSum(), SCIPgetConstantExprSum() instead
693- removed SCIPexprgraphGetNodeQuadraticConstant(), SCIPexprgraphGetNodeQuadraticLinearCoefs(), SCIPexprgraphGetNodeQuadraticQuadElements(), SCIPexprgraphGetNodeQuadraticNQuadElements(), use SCIPexprGetQuadraticData(), SCIPexprGetQuadraticQuadTerm(), SCIPexprGetQuadraticBilinTerm() instead
694- removed SCIPexprgraphGetNodePolynomialMonomials(), SCIPexprgraphGetNodePolynomialNMonomials(), SCIPexprgraphGetNodePolynomialConstant(), SCIPexprgraphGetNodePolynomialMonomialCurvature()
695- removed SCIPexprgraphGetNodeUserData(), SCIPexprgraphHasNodeUserEstimator()
696- removed SCIPexprgraphGetNodeBounds(), use SCIPexprGetActivity() instead
697- removed SCIPexprgraphGetNodeVal(), use SCIPexprGetEvalValue() instead
698- removed SCIPexprgraphGetNodeCurvature(), use SCIPexprGetCurvature() instead
699- removed SCIPexprgraphCreateNode()
700- removed SCIPexprgraphCreateNodeLinear(), use SCIPcreateExprSum() instead
701- removed SCIPexprgraphCreateNodeQuadratic(), use SCIPcreateExprQuadratic() instead
702- removed SCIPexprgraphCreateNodePolynomial(), SCIPexprgraphNodePolynomialAddMonomials()
703- removed SCIPexprgraphCreateNodeUser(), removed SCIPexprgraphNodeSplitOffLinear(), SCIPexprgraphMoveNodeParents()
704- removed SCIPexprgraphReleaseNode(), use SCIPreleaseExpr() instead
705- removed SCIPexprgraphFreeNode(), use SCIPreleaseExpr() instead
706- removed SCIPexprgraphEnableNode(), SCIPexprgraphDisableNode()
707- removed SCIPexprgraphHasNodeSibling(), SCIPexprgraphAreAllNodeChildrenVars(), SCIPexprgraphHasNodeNonlinearAncestor()
708- removed SCIPexprgraphPrintNode(), SCIPprintExpr() instead
709- removed SCIPexprgraphTightenNodeBounds()
710- removed SCIPexprgraphUpdateNodeBoundsCurvature(), use SCIPevalExprActivity() and SCIPcomputeExprCurvature() instead
711- removed SCIPexprgraphGetDepth(), SCIPexprgraphGetNNodes(), SCIPexprgraphGetNodes(), SCIPexprgraphGetNVars(), SCIPexprgraphGetVars()
712- removed SCIPexprgraphGetVarNodes(), SCIPexprgraphSetVarNodeValue(), SCIPexprgraphSetVarsBounds(), SCIPexprgraphSetVarBounds(), SCIPexprgraphSetVarNodeBounds(), SCIPexprgraphSetVarNodeLb(), SCIPexprgraphSetVarNodeUb(), SCIPexprgraphGetVarsBounds()
713- removed SCIPexprgraphCreate(), SCIPexprgraphFree()
714- removed SCIPexprgraphAddNode(), SCIPexprgraphAddVars(), SCIPexprgraphAddConst(), SCIPexprgraphAddExprtreeSum()
715- removed SCIPexprgraphReplaceVarByLinearSum(), SCIPexprgraphFindVarNode(), SCIPexprgraphFindConstNode()
716- replaced SCIPexprgraphPrintDot() by SCIPprintExprDotInit[2](), SCIPprintExprDot(), SCIPprintExprDotFinal()
717- removed SCIPexprgraphEval(), use SCIPevalExpr() instead
718- removed SCIPexprgraphPropagateVarBounds(), SCIPexprgraphPropagateNodeBounds()
719- removed SCIPexprgraphCheckCurvature(), use SCIPcomputeExprCurvature() instead
720- removed SCIPexprgraphSimplify(), use SCIPsimplifyExpr() instead
721- removed SCIPexprgraphGetTree(), SCIPexprgraphGetSeparableTrees(), SCIPexprgraphGetSubtreeVarsUsage(), SCIPexprgraphGetSumTreesNSummands(), SCIPexprgraphGetSumTrees()
722
723Constraint handlers for NLP:
724- removed SCIPincludeConshdlrAbspower()
725- deprecated SCIPcreateConsAbspower() and SCIPcreateConsBasicAbspower(), use SCIPcreateConsBasicSignpowerNonlinear() instead
726- deprecated SCIPgetNlRowAbspower(), use SCIPgetNlRowNonlinear() instead
727- removed SCIPgetNonlinearVarAbspower(), SCIPgetLinearVarAbspower(), SCIPgetExponentAbspower(), SCIPgetOffsetAbspower(), SCIPgetCoefLinearAbspower(), SCIPgetLhsAbspower(), SCIPgetRhsAbspower()
728- removed SCIPgetViolationAbspower(), use SCIPgetAbsViolationNonlinear() instead
729- removed SCIPisConvexAbspower(), use SCIPhasExprCurvature() instead
730- removed SCIPincludeConshdlrBivariate(), SCIPcreateConsBivariate(), SCIPcreateConsBasicBivariate()
731- removed SCIPgetLinearVarBivariate(), SCIPgetLinearCoefBivariate(), SCIPgetExprtreeBivariate(), SCIPgetLhsBivariate(), SCIPgetRhsBivariate()
732- removed SCIPincludeConshdlrQuadratic(), use SCIPincludeNlhdlrQuadratic() instead
733- removed SCIPincludeQuadconsUpgrade()
734- removed SCIPcreateConsQuadratic2(), SCIPcreateConsBasicQuadratic2()
735- deprecated SCIPcreateConsBasicQuadratic(), use SCIPcreateConsBasicQuadraticNonlinear() instead
736- deprecated SCIPcreateConsBasicQuadratic(), use SCIPcreateConsQuadraticNonlinear() instead
737- deprecated SCIPaddConstantQuadratic(), use SCIPgetLhsNonlinear() and SCIPgetRhsNonlinear() instead
738- deprecated SCIPaddLinearVarQuadratic(), use SCIPaddLinearVarNonlinear() instead
739- deprecated SCIPaddQuadVarQuadratic(), use SCIPaddLinearVarNonlinear() and SCIPaddExprNonlinear() instead
740- deprecated SCIPaddQuadVarLinearCoefQuadratic(), use SCIPaddLinearVarNonlinear() instead
741- deprecated SCIPaddSquareCoefQuadratic(), use SCIPaddExprNonlinear() instead
742- deprecated SCIPaddBilinTermQuadratic(), use SCIPaddExprNonlinear() instead
743- deprecated SCIPchgLhsQuadratic(), use SCIPgetLhsNonlinear() instead
744- deprecated SCIPchgRhsQuadratic(), use SCIPgetRhsNonlinear() instead
745- deprecated SCIPgetNlRowQuadratic(), use SCIPgetNlRowNonlinear() instead
746- removed SCIPgetNLinearVarsQuadratic(), SCIPgetLinearVarsQuadratic(), SCIPgetCoefsLinearVarsQuadratic(), SCIPgetNQuadVarTermsQuadratic(), SCIPgetQuadVarTermsQuadratic(), SCIPsortQuadVarTermsQuadratic(), SCIPfindQuadVarTermQuadratic(), SCIPgetNBilinTermsQuadratic(), SCIPgetBilinTermsQuadratic(), SCIPgetLhsQuadratic(), SCIPgetRhsQuadratic()
747- removed SCIPgetLinvarMayDecreaseQuadratic(), SCIPgetLinvarMayIncreaseQuadratic()
748- removed SCIPcheckCurvatureQuadratic() and SCIPisConvexConsQuadratic(), use SCIPcomputeExprQuadraticCurvature() instead
749- removed SCIPisConvexQuadratic(), SCIPisConcaveQuadratic()
750- removed SCIPgetViolationQuadratic() and SCIPgetFeasibilityQuadratic(), use SCIPgetAbsViolationNonlinear() instead
751- removed SCIPisLinearLocalQuadratic(), SCIPaddToNlpiProblemQuadratic()
752- removed SCIPchgLinearCoefQuadratic(), SCIPchgSquareCoefQuadratic(), SCIPchgBilinCoefQuadratic()
753- renamed SCIPgetNAllBilinearTermsQuadratic() to SCIPgetNBilinTermsNonlinear() and changed argument from SCIP* to SCIP_CONSHDLR*
754- renamed SCIPgetAllBilinearTermsQuadratic() to SCIPgetBilinTermsNonlinear() and replaced arguments by SCIP_CONSHDLR* and changed return type to SCIP_CONSNONLINEAR_BILINTERM*
755- removed SCIPaddBilinearIneqQuadratic(), use SCIPinsertBilinearTermImplicitNonlinear() instead
756- renamed SCIPcreateConsQuadratic() to SCIPcreateConsQuadraticNonlinear() and removed argument stickingatnode
757- removed SCIPincludeConshdlrSOC()
758- replaced SCIPcreateConsBasicSOC() by SCIPcreateConsBasicSOCNonlinear()
759- deprecated SCIPcreateConsSOC(), use SCIPcreateConsBasicSOCNonlinear() instead
760- deprecated SCIPgetNlRowSOC(), use SCIPgetNlRowNonlinear() instead
761- removed SCIPgetNLhsVarsSOC(), SCIPgetLhsVarsSOC(), SCIPgetLhsCoefsSOC(), SCIPgetLhsOffsetsSOC(), SCIPgetLhsConstantSOC(), SCIPgetRhsVarSOC(), SCIPgetRhsCoefSOC(), SCIPgetRhsOffsetSOC(), use SCIPisSOCNonlinear() instead
762- removed SCIPaddToNlpiProblemSOC()
763- renamed SCIPincludeNonlinconsUpgrade() to SCIPincludeConsUpgradeNonlinear() and removed nodereform argument
764- removed arguments nlinvars, linvars, lincoefs, nexprtrees, exprtrees, nonlincoefs, stickingatnode from SCIPcreateConsNonlinear() and added SCIP_EXPR* argument
765- removed arguments nlinvars, linvars, lincoefs, nexprtrees, exprtrees, nonlincoefs from SCIPcreateConsBasicNonlinear() and added SCIP_EXPR* argument
766- removed SCIPcreateConsNonlinear2(), SCIPcreateConsBasicNonlinear2()
767- removed SCIPsetExprtreesNonlinear(), use SCIPchgExprNonlinear() instead
768- removed SCIPaddExprtreesNonlinear()
769- removed SCIPgetNLinearVarsNonlinear(), SCIPgetLinearVarsNonlinear(), SCIPgetLinearCoefsNonlinear()
770- removed SCIPgetNExprtreesNonlinear(), SCIPgetExprtreesNonlinear(), SCIPgetExprtreeCoefsNonlinear(), SCIPgetExprgraphNodeNonlinear(), use SCIPgetExprNonlinear() instead
771- removed argument scip from SCIPgetLhsNonlinear() and SCIPgetRhsNonlinear()
772- removed SCIPcheckCurvatureNonlinear(), SCIPgetCurvatureNonlinear(), and SCIPgetExprtreeCurvaturesNonlinear(), use SCIPhasExprCurvature() instead
773- renamed SCIPgetViolationNonlinear() to SCIPgetAbsViolationNonlinear()
774- added arguments var and coef to SCIPgetLinvarMayDecreaseNonlinear() and SCIPgetLinvarMayIncreaseNonlinear() and changed return type to void
775- removed SCIPgetExprgraphNonlinear()
776- removed SCIPcomputeHyperplaneThreePoints(), use SCIPcomputeFacetVertexPolyhedralNonlinear() instead
777
778### New API functions
779
780- added SCIPallocClearMemory() and SCIPallocClearBlockMemory() to allocate a chunk of (block) memory
781 that is initialized to zeros
782- New internal functions for changing the default values of parameters:
783 SCIPparamsetSetDefaultLongint(), SCIPparamsetSetDefaultReal(), SCIPparamsetSetDefaultChar(),
784 SCIPparamsetSetDefaultString() and
785 SCIPparamSetDefaultLongint(), SCIPparamSetDefaultReal(), SCIPparamSetDefaultChar(),
786 SCIPparamSetDefaultString()
787- new internal function SCIPisPackingPartitioningOrbitope() to check whether an orbitope is of
788 packing or partitioning type
789- new internal function SCIPcomputeOrbitVar() to compute the symmetry orbit of a variable
790- added SCIPcalcFibHash(SCIP_Real) to hash a floating-point value to an unsigned integer
791- added SCIPcomputeArraysIntersectionPtr() to compute intersection of two sorted arrays of pointers
792- new function SCIPinterruptLP() (intended to be called from a different thread) that interrupts ongoing lp solve
793- added SCIPcreateConsIndicatorGeneric() and SCIPcreateConsIndicatorGenericLinCons()
794 which copy the interface of SCIPcreateConsIndicator() and SCIPcreateConsIndicatorLinCons() and
795 add an activeone argument to specify whether the indicator constraint should be activated on 0 or 1.
796 SCIPcreateConsIndicator() also adds a lessthanineq flag to choose whether the linear constraint is a less-than or greater-than inequality.
797- added SCIPmarkDoNotAggrVar() to mark that a variable should not be aggregated
798- added SCIPdoNotAggrVar() to query whether a variable should not be aggregated
799- added SCIPdecompGetNBorderVars() and SCIPdecompGetNBorderConss() to get number of border variables/constraints
800- added SCIPdecompGetVarsSize() and SCIPdecompGetConssSize() to get variable/constraint size for each block of a decomposition
801- added SCIPincludeDialogDefaultBasic()
802- added SCIPintervalAreDisjointEps(), SCIPintervalIntersectEps()
803- added SCIPintervalEntropy()
804- added SCIPintervalPropagateWeightedSum()
805- added SCIPcalcRootNewton()
806- added SCIPvarGetImplicVarBounds()
807- added SCIPcreateRowprep(), SCIPfreeRowprep(), SCIPcopyRowprep(),
808 SCIProwprepGetNVars(), SCIProwprepGetVars(), SCIProwprepGetCoefs(), SCIProwprepGetSide(), SCIProwprepGetSidetype(), SCIProwprepIsLocal(), SCIProwprepGetName(), SCIProwprepGetNModifiedVars(), SCIProwprepGetModifiedVars(),
809 SCIProwprepReset(), SCIProwprepAddSide(), SCIProwprepAddConstant(), SCIProwprepSetSidetype(), SCIProwprepSetLocal(), SCIProwprepRecordModifications(),
810 SCIPprintRowprep(), SCIPprintRowprepSol(), SCIPensureRowprepSize(), SCIPaddRowprepTerm(), SCIPaddRowprepTerms(), SCIPgetRowprepViolation(), SCIPisRowprepViolationReliable(),
811 SCIPmergeRowprepTerms(), SCIPcleanupRowprep(), SCIPcleanupRowprep2(), SCIPscaleupRowprep(), SCIPscaleRowprep(),
812 SCIPgetRowprepRowConshdlr(), SCIPgetRowprepRowCons(), SCIPgetRowprepRowSepa()
813- added SCIPsetClockEnabled()
814- added SCIPisSolveInterrupted() to check whether SCIPinterruptSolve() has been called
815- added SCIPgetNPresolRounds()
816- added SCIPgetNUnfixedLPCols()
817- moved SCIPhistoryGetInferenceSum() and SCIPhistoryGetAvgConflictlength() from internal to public API
818
819Expression handler:
820- added SCIPincludeExprhdlr(), SCIPgetExprhdlrs(), SCIPgetNExprhdlrs(), SCIPfindExprhdlr()
821- added SCIPgetExprhdlrVar(), SCIPgetExprhdlrValue(), SCIPgetExprhdlrSum(), SCIPgetExprhdlrProduct(), SCIPgetExprhdlrPower()
822- added SCIPexprhdlrSetCopyFreeHdlr(), SCIPexprhdlrSetCopyFreeData(), SCIPexprhdlrSetPrint(), SCIPexprhdlrSetParse(), SCIPexprhdlrSetCurvature(), SCIPexprhdlrSetMonotonicity(), SCIPexprhdlrSetIntegrality(), SCIPexprhdlrSetHash(), SCIPexprhdlrSetCompare(), SCIPexprhdlrSetDiff(), SCIPexprhdlrSetIntEval(), SCIPexprhdlrSetSimplify(), SCIPexprhdlrSetReverseProp(), SCIPexprhdlrSetEstimate()
823- added SCIPexprhdlrGetName(), SCIPexprhdlrGetDescription(), SCIPexprhdlrGetPrecedence(), SCIPexprhdlrGetData(), SCIPexprhdlrHasPrint(), SCIPexprhdlrHasBwdiff(), SCIPexprhdlrHasFwdiff(), SCIPexprhdlrHasIntEval(), SCIPexprhdlrHasEstimate(), SCIPexprhdlrHasInitEstimates(), SCIPexprhdlrHasSimplify(), SCIPexprhdlrHasCurvature(), SCIPexprhdlrHasMonotonicity(), SCIPexprhdlrHasReverseProp()
824- added SCIPexprhdlrComp()
825- added SCIPexprhdlrGetNIntevalCalls(), SCIPexprhdlrGetIntevalTime(), SCIPexprhdlrGetNReversepropCalls(), SCIPexprhdlrGetReversepropTime(), SCIPexprhdlrGetNCutoffs(), SCIPexprhdlrGetNDomainReductions(), SCIPexprhdlrIncrementNDomainReductions(), SCIPexprhdlrGetNEstimateCalls(), SCIPexprhdlrGetEstimateTime(), SCIPexprhdlrGetNBranchings(), SCIPexprhdlrIncrementNBranchings(), SCIPexprhdlrGetNSimplifyCalls(), SCIPexprhdlrGetSimplifyTime(), SCIPexprhdlrGetNSimplifications()
826- added SCIPprintExpressionHandlerStatistics()
827- added SCIPincludeExprhdlrEntropy(), SCIPcreateExprEntropy(), SCIPisExprEntropy()
828- added SCIPincludeExprhdlrErf(), SCIPcreateExprErf(), SCIPisExprErf()
829- added SCIPcreateExprAbs(), SCIPincludeExprhdlrAbs(), SCIPisExprAbs()
830- added SCIPcreateExprExp(), SCIPincludeExprhdlrExp(), SCIPisExprExp()
831- added SCIPcreateExprLog(), SCIPincludeExprhdlrLog(), SCIPisExprLog()
832- added SCIPcreateExprPow(), SCIPcreateExprSignpower(), SCIPincludeExprhdlrPow(), SCIPincludeExprhdlrSignpower(), SCIPisExprSignpower(), SCIPgetExponentExprPow(), SCIPisExprPower()
833- added SCIPincludeExprhdlrProduct(), SCIPcreateExprProduct(), SCIPgetCoefExprProduct(), SCIPisExprProduct()
834- added SCIPincludeExprhdlrSum(), SCIPcreateExprSum(), SCIPsetConstantExprSum(), SCIPappendExprSumExpr(), SCIPmultiplyByConstantExprSum(), SCIPgetCoefsExprSum(), SCIPgetConstantExprSum(), SCIPisExprSum()
835- added SCIPincludeExprhdlrSin(), SCIPcreateExprSin(), SCIPincludeExprhdlrCos(), SCIPcreateExprCos(), SCIPisExprSin(), SCIPisExprCos()
836- added SCIPincludeExprhdlrValue(), SCIPcreateExprValue(), SCIPgetValueExprValue(), SCIPisExprValue()
837- added SCIPincludeExprhdlrVar(), SCIPcreateExprVar(), SCIPgetVarExprVar(), SCIPisExprVar()
838- added SCIPincludeExprhdlrVaridx(), SCIPcreateExprVaridx(), SCIPisExprVaridx(), SCIPgetIndexExprVaridx(), SCIPsetIndexExprVaridx()
839
840Expression:
841- added SCIPcaptureExpr(), SCIPreleaseExpr(), SCIPexprGetNUses()
842- added SCIPexprGetHdlr(), SCIPexprGetData(), SCIPexprSetData(), SCIPexprGetOwnerData()
843- added SCIPevalExpr(), SCIPgetExprNewSoltag(), SCIPexprGetEvalValue(), SCIPexprGetEvalTag()
844- added SCIPevalExprGradient(), SCIPevalExprHessianDir(), SCIPexprGetDerivative(), SCIPexprGetDot(), SCIPexprGetBardot(), SCIPexprGetDiffTag()
845- added SCIPevalExprActivity(), SCIPexprGetActivity(), SCIPexprGetActivityTag(), SCIPexprSetActivity()
846- added SCIPcomputeExprCurvature(), SCIPexprGetCurvature(), SCIPexprSetCurvature()
847- added SCIPcomputeExprIntegrality(), SCIPexprIsIntegral(), SCIPexprSetIntegrality()
848- added SCIPcheckExprQuadratic(), SCIPfreeExprQuadratic(), SCIPevalExprQuadratic(), SCIPprintExprQuadratic(), SCIPcomputeExprQuadraticCurvature()
849- added SCIPexprGetQuadraticData(), SCIPexprGetQuadraticQuadTerm(), SCIPexprGetQuadraticBilinTerm(), SCIPexprAreQuadraticExprsVariables()
850- added SCIPcreateExpr(), SCIPcreateExpr2(), SCIPcreateExprQuadratic(), SCIPcreateExprMonomial()
851- added SCIPappendExprChild(), SCIPreplaceExprChild(), SCIPremoveExprChildren()
852- added SCIPduplicateExpr(), SCIPduplicateExprShallow(), SCIPcopyExpr()
853- added SCIPparseExpr()
854- added SCIPprintExpr(), SCIPdismantleExpr()
855- added SCIPprintExprDotInit(), SCIPprintExprDotInit2(), SCIPprintExprDot(), SCIPprintExprDotFinal(), SCIPshowExpr()
856- added SCIPcompareExpr(), SCIPhashExpr()
857- added SCIPsimplifyExpr(), SCIPreplaceCommonSubexpressions()
858- added SCIPgetExprNVars(), SCIPgetExprVarExprs()
859- added SCIPcallExprPrint(), SCIPcallExprCurvature(), SCIPcallExprMonotonicity(), SCIPcallExprEval(), SCIPcallExprEvalFwdiff(), SCIPcallExprInteval(), SCIPcallExprEstimate(), SCIPcallExprInitestimates(), SCIPcallExprSimplify(), SCIPcallExprReverseprop()
860- added SCIPexprcurvPowerInv(), SCIPexprcurvMonomialInv()
861
862Expression iterator:
863- added SCIPcreateExpriter(), SCIPfreeExpriter()
864- added SCIPexpriterIsInit(), SCIPexpriterInit()
865- added SCIPexpriterRestartDFS(), SCIPexpriterSetStagesDFS(), SCIPexpriterGetCurrent(), SCIPexpriterGetStageDFS(), SCIPexpriterGetChildIdxDFS(), SCIPexpriterGetChildExprDFS(), SCIPexpriterGetParentDFS()
866- added SCIPexpriterGetCurrentUserData(), SCIPexpriterGetChildUserDataDFS(), SCIPexpriterGetExprUserData(), SCIPexpriterSetCurrentUserData(), SCIPexpriterSetExprUserData(), SCIPexpriterSetChildUserData()
867- added SCIPexpriterGetNext(), SCIPexpriterSkipDFS(), SCIPexpriterIsEnd()
868- added SCIPexprintHessianSparsity(), SCIPexprintHessian()
869
870Constraint handlers for NLP:
871- added SCIPgetCurBoundsTagNonlinear(), SCIPgetLastBoundRelaxTagNonlinear(), SCIPincrementCurBoundsTagNonlinear()
872- added SCIPgetVarExprHashmapNonlinear()
873- added SCIPprocessRowprepNonlinear()
874- added SCIPassumeConvexNonlinear()
875- added SCIPcollectBilinTermsNonlinear(), SCIPgetBilinTermIdxNonlinear(), SCIPgetBilinTermNonlinear(), SCIPevalBilinAuxExprNonlinear(), SCIPinsertBilinearTermExistingNonlinear(), SCIPinsertBilinearTermImplicitNonlinear()
876- added SCIPcomputeFacetVertexPolyhedralNonlinear()
877- added SCIPgetExprNonlinear()
878- added SCIPcheckQuadraticNonlinear(), SCIPchgLhsNonlinear(), SCIPchgRhsNonlinear(), SCIPchgExprNonlinear(), SCIPaddExprNonlinear()
879- added SCIPgetRelViolationNonlinear()
880- added SCIPgetExprNLocksPosNonlinear(), SCIPgetExprNLocksNegNonlinear(), SCIPgetExprAuxVarNonlinear(), SCIPgetExprNEnfosNonlinear(), SCIPgetExprEnfoDataNonlinear(), SCIPsetExprEnfoAuxValueNonlinear()
881- added SCIPgetExprNPropUsesActivityNonlinear(), SCIPgetExprNSepaUsesActivityNonlinear(), SCIPgetExprNAuxvarUsesNonlinear(), SCIPregisterExprUsageNonlinear()
882- added SCIPgetExprAbsOrigViolationNonlinear(), SCIPgetExprAbsAuxViolationNonlinear(), SCIPgetExprRelAuxViolationNonlinear()
883- added SCIPgetExprBoundsNonlinear(), SCIPtightenExprIntervalNonlinear(), SCIPmarkExprPropagateNonlinear()
884- added SCIPaddExprViolScoreNonlinear(), SCIPaddExprsViolScoreNonlinear(), SCIPgetExprViolScoreNonlinear()
885- added SCIPgetExprPartialDiffNonlinear(), SCIPgetExprPartialDiffGradientDirNonlinear()
886- added SCIPevalExprQuadraticAuxNonlinear()
887- added SCIPincludeNlhdlrNonlinear(), SCIPfindNlhdlrNonlinear(), SCIPgetNNlhdlrsNonlinear(), SCIPgetNlhdlrsNonlinear(), SCIPgetNlhdlrExprDataNonlinear()
888- added SCIPcreateConsQuadraticNonlinear() and SCIPcreateConsBasicQuadraticNonlinear() to create a nonlinear constraint that is quadratic
889- added SCIPcreateConsBasicSignpowerNonlinear() to create a nonlinear constraint that looks like the former abspower or signpower constraints
890
891Nonlinear Handler:
892- added SCIPincludeNlhdlrBilinear(), SCIPgetExprsBilinear(), SCIPgetExprsdataBilinear(), SCIPgetNExprsBilinear(), SCIPaddIneqBilinear()
893- added SCIPincludeNlhdlrConvex(), SCIPincludeNlhdlrConcave(), SCIPhasExprCurvature()
894- added SCIPincludeNlhdlrDefault()
895- added SCIPincludeNlhdlrPerspective()
896- added SCIPincludeNlhdlrQuadratic()
897- added SCIPincludeNlhdlrQuotient()
898- added SCIPincludeNlhdlrSoc(), SCIPisSOCNonlinear(), SCIPfreeSOCArraysNonlinear()
899- added SCIPnlhdlrSetCopyHdlr(), SCIPnlhdlrSetFreeHdlrData(), SCIPnlhdlrSetFreeExprData(), SCIPnlhdlrSetInitExit(), SCIPnlhdlrSetProp(), SCIPnlhdlrSetSepa()
900- added SCIPnlhdlrGetName(), SCIPnlhdlrGetDesc(), SCIPnlhdlrGetDetectPriority(), SCIPnlhdlrGetEnfoPriority(), SCIPnlhdlrIsEnabled(), SCIPnlhdlrGetData()
901- added SCIPnlhdlrHasIntEval(), SCIPnlhdlrHasReverseProp(), SCIPnlhdlrHasInitSepa(), SCIPnlhdlrHasExitSepa(), SCIPnlhdlrHasEnfo(), SCIPnlhdlrHasEstimate()
902- added SCIPnlhdlrComp()
903
904NLPI:
905- added SCIPgetNlpiSolverPointer(), SCIPcreateNlpiProblem(), SCIPfreeNlpiProblem(), SCIPgetNlpiProblemPointer(), SCIPaddNlpiVars(), SCIPaddNlpiConstraints(), SCIPsetNlpiObjective(), SCIPchgNlpiVarBounds(), SCIPchgNlpiConsSides(), SCIPdelNlpiVarSet(), SCIPdelNlpiConsSet(), SCIPchgNlpiLinearCoefs(), SCIPchgNlpiExpr(), SCIPchgNlpiObjConstant(), SCIPsetNlpiInitialGuess(), SCIPsolveNlpiParam(), SCIPgetNlpiSolstat(), SCIPgetNlpiTermstat(), SCIPgetNlpiSolution(), SCIPgetNlpiStatistics()
906- added SCIPincludeNlpSolverAll()
907- added SCIPincludeNlpSolverFilterSQP(), SCIPgetSolverNameFilterSQP(), SCIPgetSolverDescFilterSQP(), SCIPisFilterSQPAvailableFilterSQP()
908- added SCIPincludeNlpSolverIpopt()
909- added SCIPincludeNlpSolverWorhp()
910- added SCIPnlpiOracleChgExpr()
911- added SCIPcreateNlpiProblemFromNlRows()
912- added SCIPnlpiOracleGetObjectiveConstant()
913- added SCIPnlpiOracleIsVarNonlinear(), SCIPnlpiOracleGetVarCounts(), SCIPnlpiOracleIsConstraintNonlinear()
914- added SCIPnlpiGetNProblems(), SCIPnlpiGetProblemTime(), SCIPnlpiGetNSolves(), SCIPnlpiGetSolveTime(), SCIPnlpiGetEvalTime(), SCIPnlpiGetNIterations(), SCIPnlpiGetNTermStat(), SCIPnlpiGetNSolStat(), SCIPnlpiMergeStatistics()
915- added SCIPmergeNLPIStatistics(), SCIPprintNLPIStatistics()
916- added SCIPnlpiOracleResetEvalTime(), SCIPnlpiOracleGetEvalTime()
917- added SCIPaddNlpiProblemNlRows()
918
919Cut Selector:
920- added SCIPincludeCutsel(), SCIPincludeCutselBasic(), SCIPsetCutselCopy(), SCIPsetCutselFree(), SCIPsetCutselInit(), SCIPsetCutselExit(), SCIPsetCutselInitsol(), SCIPsetCutselExitsol(), SCIPfindCutsel(), SCIPgetCutsels(), SCIPgetNCutsels(), SCIPsetCutselPriority()
921- added SCIPcutselGetName(), SCIPcutselGetData(), SCIPcutselGetDesc(), SCIPcutselGetPriority(), SCIPcutselSetData(), SCIPcutselIsInitialized(), SCIPcutselGetSetupTime(), SCIPcutselGetTime()
922
923### Command line interface
924### Interfaces to external software
925
926- removed GAMS interface (originally in interfaces/gams) and reading capability of gms reader;
927 the removed interface was a poorly maintained copy of the GAMS/SCIP interface that is available at
928 https://github.com/coin-or/GAMSlinks
929- integrated AMPL interface into main SCIP executable, that is, added possibility to use SCIP executable as solver in AMPL
930 (AMPL calls solver with name of .nl file and -AMPL as arguments; SCIP will then attempt to solve the problem and write an AMPL solution file)
931- the ZIMPL interface has been updated to support ZIMPL 3.4.1;
932 the minimal required ZIMPL version is now 3.4.1
933
934### Changed parameters
935
936- Extended range of parameter "misc/usesymmetry" from [0,3] to [0,7], changed default from 3 to 5
937- deleted parameter "constraints/orbitope/usedynamicprop"
938- changed type of parameter "propagating/symmetry/recomputerestart" from SCIP_Bool to int with range [0,2]
939- deleted parameter "propagating/symmetry/disableofrestart"
940- parameter "heuristics/padm/original" is now an advanced parameter
941- removed constraints/nonlinear/linfeasshift, constraints/nonlinear/reformulate, constraints/nonlinear/maxexpansionexponent, constraints/nonlinear/sepanlpmincont
942- removed constraints/nonlinear/upgrade/abspower
943- removed constraints/nonlinear/upgrade/and, use constraints/nonlinear/reformbinprodsand instead
944- removed constraints/nonlinear/upgrade/bivariate
945- removed constraints/nonlinear/upgrade/quadratic, use nlhdlr/quadratic/enabled instead
946- changed default of constraints/nonlinear/maxproprounds from 1 to 10
947- replaced constraints/nonlinear/enfocutsremovable by constraints/nonlinear/rownotremovable
948- replaced constraints/nonlinear/cutmaxrange by separating/maxcoefratiofacrowprep
949- removed constraints/quadratic/sepafreq, constraints/quadratic/propfreq, constraints/quadratic/proptiming, constraints/quadratic/eagerfreq, constraints/quadratic/maxprerounds, constraints/quadratic/delaysepa, constraints/quadratic/delayprop, constraints/quadratic/presoltiming
950- removed constraints/quadratic/replacebinaryprod, use constraints/nonlinear/reformbinprodsfac instead
951- removed constraints/quadratic/empathy4and, use constraints/nonlinear/reformbinprodsand instead
952- removed constraints/quadratic/binreforminitial, constraints/quadratic/binreformbinaryonly, constraints/quadratic/binreformmaxcoef
953- removed constraints/quadratic/cutmaxrange, constraints/quadratic/mincurvcollectbilinterms, constraints/quadratic/linearizeheursol, constraints/quadratic/checkcurvature, constraints/quadratic/checkfactorable, constraints/quadratic/checkquadvarlocks, constraints/quadratic/linfeasshift
954- removed constraints/quadratic/maxdisaggrsize, constraints/quadratic/disaggrmergemethod, constraints/quadratic/maxproprounds, constraints/quadratic/maxproproundspresolve, constraints/quadratic/enfolplimit, constraints/quadratic/sepanlpmincont, constraints/quadratic/enfocutsremovable
955- removed constraints/quadratic/gaugecuts, constraints/quadratic/interiorcomputation, constraints/quadratic/projectedcuts, constraints/quadratic/branchscoring, constraints/quadratic/usebilinineqbranch, constraints/quadratic/bilinineqmaxseparounds,
956- removed constraints/quadratic/minscorebilinterms, use nlhdlr/bilinear/enabled instead
957- removed constraints/quadratic/upgrade/linear, constraints/quadratic/upgrade/abspower, constraints/quadratic/upgrade/bivariate, constraints/quadratic/upgrade/bounddisjunction
958- removed constraints/quadratic/upgrade/soc, use nlhdlr/soc/enabled instead
959- renamed constraints/quadratic/upgrade/setppc to constraints/nonlinear/upgrade/setppc
960- removed constraints/abspower/sepafreq, constraints/abspower/propfreq, constraints/abspower/proptiming, constraints/abspower/eagerfreq, constraints/abspower/maxprerounds, constraints/abspower/delaysepa, constraints/abspower/delayprop, constraints/abspower/presoltiming
961- removed constraints/abspower/cutmaxrange, constraints/abspower/projectrefpoint, constraints/abspower/preferzerobranch, constraints/abspower/branchminconverror, constraints/abspower/addvarboundcons, constraints/abspower/linfeasshift, constraints/abspower/dualpresolve, constraints/abspower/sepainboundsonly, constraints/abspower/sepanlpmincont, constraints/abspower/enfocutsremovable
962- removed constraints/bivariate/sepafreq, constraints/bivariate/propfreq, constraints/bivariate/proptiming, constraints/bivariate/eagerfreq, constraints/bivariate/maxprerounds, constraints/bivariate/delaysepa, constraints/bivariate/delayprop, constraints/bivariate/presoltiming
963- removed constraints/bivariate/cutmaxrange, constraints/bivariate/linfeasshift, constraints/bivariate/maxproprounds, constraints/bivariate/ninitlprefpoints, constraints/bivariate/enfocutsremovable
964- removed constraints/soc/sepafreq, constraints/soc/propfreq, constraints/soc/proptiming, constraints/soc/eagerfreq, constraints/soc/maxprerounds, constraints/soc/delaysepa, constraints/soc/delayprop, constraints/soc/presoltiming
965- removed constraints/soc/projectpoint, constraints/soc/nauxvars, constraints/soc/glineur, constraints/soc/sparsify, constraints/soc/sparsifymaxloss, constraints/soc/sparsifynzgrowth, constraints/soc/linfeasshift, constraints/soc/nlpform, constraints/soc/sepanlpmincont, constraints/soc/enfocutsremovable, constraints/soc/disaggregate
966- removed constraints/soc/generalsocupgrade, use nlhdlr/soc/compeigenvalues instead
967- changed default of presolving/qpkktref/maxrounds from -1 to 0
968- changed default of propagating/obbt/onlynonconvexvars from FALSE to TRUE
969- changed default of heuristics/subnlp/resolvetolfactor from 0.001 to 1.0
970- removed heuristics/subnlp/nlpoptfile, use nlpi/ipopt/optfile instead
971- removed separating/convexproj/nlptimelimit
972- removed separating/gauge/nlptimelimit
973- removed heuristics/subnlp/nlptimelimit and heuristics/subnlp/nlpiterlimit
974- removed heuristics/subnlp/resolvetolfactor and heuristics/subnlp/resolvefromscratch
975- changed default of heuristics/subnlp/itermin to 20
976- renamed heuristics/subnlp/iteroffset to heuristics/subnlp/nodesoffset
977- renamed heuristics/subnlp/iterquotient to heuristics/subnlp/nodesfactor
978- removed heuristics/subnlp/runalways, use heuristics/subnlp/nodesoffset=INT_MAX and heuristics/subnlp/successrateexp = 0.0 instead
979- removed heuristics/subnlp/minimprove, heuristics/multistart/nlpminimpr
980- Removed parameters for strongcg separator: separating/strongcg/..., i.e.,
981 maxrounds, maxroundsroot, maxsepacutsroot, maxsepacuts, dynamiccuts. One can control the
982 strongcg behavior throught the parameters of sepa_gomory.
983- renamed separating/{minortho,minorthoroot,objparalfac,intsupportfac} to cutselection/hybrid/{minortho,minorthoroot,objparalweight,intsupportweight}
984
985### New parameters
986
987- It is now possible to add orbitope constraints to handle symmetries even if not all variables
988 in a component of the symmetry group are binary. This feature can be enabled using the
989 parameter "propagating/symmetry/onlybinorbitope".
990
991- new parameter "propagating/symmetry/sstleaderrule" to select a rule for selecting the
992 leader in SST cuts
993- new parameter "propagating/symmetry/ssttiebreakrule" to select a tiebreak rule for selecting the
994 leader in SST cuts
995- new parameter "propagating/symmetry/sstleadervartype" to select the possible variable types
996 for a leader in SST cuts
997- new parameter "propagating/symmetry/addconflictcuts" to control whether SST cuts are added if
998 a binary leader variable is in conflict with a variable in its orbit
999- new parameter "propagating/symmetry/sstaddcuts" to control whether SST cuts are added
1000- new parameter "propagating/symmetry/sstmixedcomponents" to control whether SST cuts are added
1001 if a symmetry component contains variables of different types
1002- new parameter "propagating/symmetry/detectsubgroups" to search for orbitopes defined by subgroups
1003- new parameter "propagating/symmetry/addweaksbcs" to add Schreier Sims cuts for a single
1004 variable orbit in case an orbitope subgroup is detected
1005- new parameter "propagating/symmetry/addstrongsbcs" to add symretope facets for a single
1006 variable orbit on which the symmetry group acts like a symmetric group
1007- new parameter "propagating/symmetry/maxnconsssubgroup" to control up to which number of
1008 constraints subgroups are detected
1009- new parameter "propagating/symmetry/preferlessrows" to control whether orbitopes with
1010 smallest number of rows shall be computed by the subgroup detection heuristic
1011- new parameter "propagating/symmetry/usedynamicprop" to control if rows of full orbitope
1012 shall be ordered dynamically in propagation
1013- new parameter "separating/filtercutpoolrel" to control whether cutpool uses
1014 a dynamic strategy to separate only cuts with high relative efficacy
1015- if run from AMPL: display/statistics to enable printing detailed solve statistics after solve
1016- if run from AMPL: display/logfile to specify name of file to write SCIP log to (additionally to writing to stdout)
1017- constraints/nonlinear/propauxvars, constraints/nonlinear/varboundrelax, constraints/nonlinear/varboundrelaxamount, constraints/nonlinear/conssiderelaxamount
1018- constraints/nonlinear/vpmaxperturb, constraints/nonlinear/vpadjfacetthresh, constraints/nonlinear/vpdualsimplex
1019- constraints/nonlinear/bilinmaxnauxexprs, constraints/nonlinear/forbidmultaggrnlvar, constraints/nonlinear/checkvarlocks, constraints/nonlinear/violscale
1020- constraints/nonlinear/reformbinprods, constraints/nonlinear/reformbinprodsand, constraints/nonlinear/reformbinprodsfac
1021- constraints/nonlinear/tightenlpfeastol, constraints/nonlinear/propinenforce, constraints/nonlinear/weakcutthreshold, constraints/nonlinear/strongcutmaxcoef, constraints/nonlinear/strongcutefficacy, constraints/nonlinear/forcestrongcut, constraints/nonlinear/enfoauxviolfactor, constraints/nonlinear/weakcutminviolfactor
1022- constraints/nonlinear/branching/aux, constraints/nonlinear/branching/external, constraints/nonlinear/branching/highviolfactor, constraints/nonlinear/branching/highscorefactor, constraints/nonlinear/branching/violweight, constraints/nonlinear/branching/dualweight, constraints/nonlinear/branching/pscostweight, constraints/nonlinear/branching/domainweight, constraints/nonlinear/branching/vartypeweight, constraints/nonlinear/branching/scoreagg, constraints/nonlinear/branching/violsplit, constraints/nonlinear/branching/pscostreliable
1023- constraints/nonlinear/linearizeheursol
1024- nlhdlr/default/enabled
1025- nlhdlr/convex/enabled, nlhdlr/convex/detectsum, nlhdlr/convex/extendedform, nlhdlr/convex/cvxquadratic, nlhdlr/convex/cvxsignomial, nlhdlr/convex/cvxprodcomp, nlhdlr/convex/handletrivial
1026- nlhdlr/concave/enabled, nlhdlr/concave/detectsum, nlhdlr/concave/cvxquadratic, nlhdlr/concave/cvxsignomial, nlhdlr/concave/cvxprodcomp, nlhdlr/concave/handletrivial
1027- nlhdlr/bilinear/enabled, nlhdlr/bilinear/useinteval, nlhdlr/bilinear/usereverseprop, nlhdlr/bilinear/maxseparoundsroot, nlhdlr/bilinear/maxseparounds, nlhdlr/bilinear/maxsepadepth
1028- nlhdlr/perspective/enabled, nlhdlr/perspective/maxproprounds, nlhdlr/perspective/mindomreduction, nlhdlr/perspective/minviolprobing, nlhdlr/perspective/probingonlyinsepa, nlhdlr/perspective/probingfreq, nlhdlr/perspective/convexonly, nlhdlr/perspective/tightenbounds, nlhdlr/perspective/adjrefpoint
1029- nlhdlr/quadratic/enabled, nlhdlr/quadratic/useintersectioncuts, nlhdlr/quadratic/usestrengthening, nlhdlr/quadratic/useboundsasrays, nlhdlr/quadratic/ncutslimit, nlhdlr/quadratic/ncutslimitroot, nlhdlr/quadratic/maxrank, nlhdlr/quadratic/mincutviolation, nlhdlr/quadratic/minviolation, nlhdlr/quadratic/atwhichnodes, nlhdlr/quadratic/nstrengthlimit, nlhdlr/quadratic/ignorebadrayrestriction, nlhdlr/quadratic/ignorehighre
1030- nlhdlr/quotient/enabled
1031- nlhdlr/soc/enabled, nlhdlr/soc/mincutefficacy, nlhdlr/soc/compeigenvalues
1032- propagating/obbt/createlincons
1033- propagating/symmetry/onlybinarysymmetry
1034- separating/minor/priority, separating/minor/freq, separating/minor/maxbounddist, separating/minor/delay, separating/minor/expbackoff, separating/minor/maxminorsconst, separating/minor/maxminorsfac, separating/minor/mincutviol, separating/minor/maxrounds, separating/minor/maxroundsroot, separating/minor/ignorepackingconss
1035- separating/rlt/priority, separating/rlt/freq, separating/rlt/maxbounddist, separating/rlt/delay, separating/rlt/expbackoff, separating/rlt/maxncuts, separating/rlt/maxunknownterms, separating/rlt/maxusedvars, separating/rlt/maxrounds, separating/rlt/maxroundsroot, separating/rlt/onlyeqrows, separating/rlt/onlycontrows, separating/rlt/onlyoriginal, separating/rlt/useinsubscip, separating/rlt/useprojection, separating/rlt/detecthidden, separating/rlt/hiddenrlt, separating/rlt/addtopool, separating/rlt/goodscore, separating/rlt/badscore, separating/rlt/objparalweight, separating/rlt/efficacyweight, separating/rlt/dircutoffdistweight, separating/rlt/goodmaxparall, separating/rlt/maxparall
1036- separating/interminor/usestrengthening, separating/interminor/usebounds, separating/interminor/mincutviol, separating/interminor/maxrounds, separating/interminor/maxroundsroot
1037- table/cons_nonlinear/active, table/nlhdlr/active, table/exprhdlr/active, table/nlpi/active, table/nlhdlr_bilinear/active, table/nlhdlr_quadratic/active
1038- expr/log/minzerodistance, expr/pow/minzerodistance
1039- benders/default/maxslackvarcoef to specify maximal coefficient for slack variables; if exceeded, slack variables are fixed to zero
1040- nlpi/ipopt/optfile to specify name of Ipopt options file to use for every solve with Ipopt
1041- nlpi/ipopt/print_level, nlpi/ipopt/hsllib, nlpi/ipopt/pardisolib, nlpi/ipopt/linear_solver, nlpi/ipopt/linear_system_scaling, nlpi/ipopt/nlp_scaling_method, nlpi/ipopt/mu_strategy, nlpi/ipopt/hessian_approximation
1042- nlpi/ipopt/warm_start_push
1043- timing/nlpieval
1044- heuristics/subnlp/iterinit, heuristics/subnlp/ninitsolves, heuristics/subnlp/successrateexp
1045- heuristics/subnlp/expectinfeas, heuristics/subnlp/opttol, heuristics/subnlp/feastolfactor
1046- heuristics/subnlp/presolveemphasis, heuristics/subnlp/setcutoff
1047- new parameters "branching/inference/conflictprio" and "branching/inference/cutoffprio" that allow
1048 using the different score criteria in inference branching hierarchically
1049- new parameters "heuristics/alns/nodesquotmin", "heuristics/alns/maxcallssamesol" and "heuristics/alns/initduringroot"
1050 to control neighborhoods in ALNS
1051- new parameter "benders/default/benderscut/optimality/mir" to control whether mixed-integer rounding procedure is applied to Benders optimality cuts
1052- new parameter "misc/avoidmemout" to try to avoid running into memory limit
1053- cutselection/hybrid/dircutoffdistweight, cutselection/hybrid/efficacyweight, cutselection/hybrid/intsupportweight, cutselection/hybrid/objparalweight, cutselection/hybrid/priority
1054- new parameter "decomposition/disablemeasures" to disable expensive measures in SCIPcomputeDecompStats()
1055- new parameter "presolving/milp/probfilename" filename to write the problem to a file before MILP presolving starts
1056
1057### Data structures
1058
1059- removed quadratic terms from NLROWs
1060- removed SCIP_NLPPAR_INFINITY from SCIP_NLPPARAM enum
1061- added types SYM_OPTYPE, SYM_CONSTTYPE, SYM_RHSTYPE, SYM_EXPRDATA
1062- removed class SCIPInterval
1063- removed enum SCIP_EXPROP
1064- removed union SCIP_EXPROPDATA, added SCIP_EXPRDATA
1065- removed struct SCIP_EXPRTREE, use SCIP_EXPR instead
1066- removed structs SCIP_QUADELEM, SCIP_EXPRDATA_QUADRATIC, SCIP_EXPRDATA_MONOMIAL, SCIP_EXPRDATA_POLYNOMIAL, SCIP_EXPRDATA_USER
1067- removed structs SCIP_EXPRGRAPHNODE, SCIP_EXPRGRAPH
1068- removed type SCIP_EXPRBOUNDSTATUS
1069- removed struct SCIP_USEREXPRDATA
1070- added enum SCIP_MONOTONE
1071- added structs SCIP_EXPRHDLR, SCIP_EXPRHDLRDATA
1072- added union SCIP_EXPRITER_USERDATA
1073- added enum SCIP_EXPRITER_TYPE
1074- added structs SCIP_EXPRITERDATA, SCIP_EXPRITER
1075- added type SCIP_EXPRPRINT_WHAT, struct SCIP_EXPRPRINTDATA
1076- removed enum SCIP_BIVAR_CONVEXITY
1077- removed structs SCIP_QUADVAREVENTDATA, SCIP_QUADVARTERM, SCIP_BILINTERM
1078- added structs SCIP_CONSNONLINEAR_AUXEXPR, SCIP_CONSNONLINEAR_BILINTERM
1079- added type SCIP_NLHDLR_METHOD
1080- added structs SCIP_NLHDLR, SCIP_NLHDLRDATA, SCIP_NLHDLREXPRDATA
1081- enum SCIP_NLPPARAM has been changed to a struct that holds values of parameters for an NLP solve
1082- removed SCIP_NLPPAR_OPTFILE/optfile from SCIP_NLPPARAM
1083- added SCIP_NLPTERMSTAT_INTERRUPT to SCIP_NLPTERMSTAT enum; returned from NLP solver if SCIPinterruptSolve() has been called
1084- renamed SCIP_NLPTERMSTAT_TILIM to SCIP_NLPTERMSTAT_TIMELIMIT
1085- renamed SCIP_NLPTERMSTAT_ITLIM to SCIP_NLPTERMSTAT_ITERLIMIT
1086- renamed SCIP_NLPTERMSTAT_LOBJLIM to SCIP_NLPTERMSTAT_LOBJLIMIT
1087- renamed SCIP_NLPTERMSTAT_NUMERR to SCIP_NLPTERMSTAT_NUMERICERROR
1088- renamed SCIP_NLPTERMSTAT_EVALERR to SCIP_NLPTERMSTAT_EVALERROR
1089- renamed SCIP_NLPTERMSTAT_MEMERR to SCIP_NLPTERMSTAT_OUTOFMEMORY
1090- renamed SCIP_NLPTERMSTAT_LICERR to SCIP_NLPTERMSTAT_LICENSEERROR
1091- added evaltime to SCIP_NLPSTATISTICS
1092- added structs SCIP_CUTSEL, SCIP_CUTSELDATA
1093
1094Deleted files
1095-------------
1096
1097- interfaces/gams/∗
1098- interfaces/ampl/∗
1099- src/nlpi/∗
1100- src/scip/cons_bivariate.{c,h}
1101- src/scip/pub_misc_nonlinear.h
1102- src/scip/misc_nonlinear.c
1103- src/scip/scip_nonlinear.{c,h}
1104- src/scip/sepa_strongcg.{h|c}
1105
1106Unit tests
1107----------
1108
1109- added cons/linear/nonlinupgd.c
1110- added cons/nonlinear/addcons.c
1111- added cons/nonlinear/bilinhash.c
1112- added cons/nonlinear/check.c
1113- added cons/nonlinear/copy.c
1114- added cons/nonlinear/create_nlrow.c
1115- added cons/nonlinear/curvature.c
1116- added cons/nonlinear/glbconss.c
1117- added cons/nonlinear/hessian.c
1118- added cons/nonlinear/locks.c
1119- added cons/nonlinear/nlhdlr.c
1120- added cons/nonlinear/nlhdlr_bilinear.c
1121- added cons/nonlinear/nlhdlr_concave.c
1122- added cons/nonlinear/nlhdlr_convex.c
1123- added cons/nonlinear/nlhdlr_perspective.c
1124- added cons/nonlinear/nlhdlr_quadratic.c
1125- added cons/nonlinear/nlhdlr_quotient.c
1126- added cons/nonlinear/nlhdlr_soc.c
1127- added cons/nonlinear/parse.c
1128- added cons/nonlinear/presolve.c
1129- added cons/nonlinear/propagate.c
1130- added cons/nonlinear/readers.c
1131- added cons/nonlinear/reformbinprods.c
1132- added cons/nonlinear/repair.c
1133- added cons/nonlinear/transform.c
1134- added cons/nonlinear/vertexpolyhedral.c
1135- removed cons/nonlinear/getCoeffsAndConstantFromLinearExpr.c
1136- removed cons/soc/upgrade.c
1137- added expr/abs/estimation.c
1138- added expr/commonsubexprs.c
1139- added expr/compare.c
1140- added expr/copy.c
1141- added expr/cos/cos.c
1142- added expr/cos/estimation.c
1143- added expr/curvature.c
1144- added expr/derivative.c
1145- added expr/entropy/entropy.c
1146- added expr/entropy/estimation.c
1147- added expr/eval.c
1148- added expr/exp/estimation.c
1149- added expr/free.c
1150- added expr/getvarexprs.c
1151- added expr/hash.c
1152- added expr/hessian.c
1153- added expr/integrality.c
1154- added expr/iterator.c
1155- added expr/log/estimation.c
1156- added expr/monotonicity.c
1157- added expr/parse.c
1158- added expr/pow/estimation.c
1159- added expr/pow/pow.c
1160- added expr/product/estimation.c
1161- added expr/quad.c
1162- added expr/simplify.c
1163- added expr/sin/estimation.c
1164- added expr/sin/sin.c
1165- added expr/sum/estimation.c
1166- added nlpi/exprinterpret.c
1167- speedup test nlpi:solveQP in nlpi/nlpi.c
1168- added test projection:transitivity in prob/obbt.c
1169- added reader/nl.c
1170- added test intervalarith:sincos in scip/intervalarith.c
1171- added sepa/minor.c
1172- added sepa/rlt/cuts.c
1173- added sepa/rlt/product_detection.c
1174- added sepa/rlt/separation.c
1175- added tests test_compute_symmetry:expr{1,2,3,4} in symmetry/compute.c
1176
1177Testing
1178-------
1179
1180Build system
1181------------
1182
1183- the separate NLPI library has been integrated into the main SCIP library;
1184 uses of NLPILIBFILE or NLPILIBSRC in Makefiles that use make/make.project
1185 should be removed
1186
1187### Cmake
1188
1189- replace flag PARASCIP by THREADSAFE
1190- option AMPL is now ON by default
1191- add -D_XOPEN_SOURCE=600 cflag for compilation on systems other than windows
1192- add compile options directly instead of modifying CMAKE_C_FLAGS and CMAKE_CXX_FLAGS
1193
1194### Makefile
1195
1196- prefix PKG_CONFIG_PATH with Ipopt's pkgconfig dir instead of postfixing
1197- replace flag PARASCIP by THREADSAFE
1198- flag AMPL is now true by default
1199- libscip has been renamed to libscipbase and libscipsolver has been renamed to libscip
1200 in order to have the same library names for makefiles and cmake. For downward
1201 compatibility libscipsolver still exists (as a link).
1202
1203Fixed bugs
1204----------
1205
1206- fixed handling of multi-aggregation in cons_symresack and cons_orbisack
1207- SCIPgetLowerbound() now consistently returns infinity when status is infeasible
1208- improved the likelihood that a solution that satisfies the nonlinear constraints in the transformed (presolved) problem is also feasible for the original problem
1209- worked around a problem with derivatives of pow at 0 with non-integer exponents in CppAD
1210- fixed that setting of feasiblity and optimiality tolerance for NLP relaxation was overwritten with defaults when solving NLP
1211- fixed variance computation in t-value computation in hypothesis testing of reliability branching
1212- fixed potential overflow in cuts.c:evaluateLiftingFunctionKnapsack()
1213- do not transfer dual reductions to main SCIP in sepa_rapidlearning if strong dual reductions are forbidden
1214- fixed a bug in cons_setppc.c:removeDoubleAndSingletonsAndPerformDualpresolve() which led to wrong variable aggregations
1215- added missing redundancy check to coefficient tightening routine in cons_varbound that led to wrong variable locks
1216- added a check of numerics to avoid wrong reductions in cons_linear.c:simplifyInequalities()
1217- fixed a bug in cons_logicor.c regarding fixed variables that were not removed
1218- presol_milp.c handles variable fixings, suggested by PaPILO, more carefully to cover all cases that can appear
1219- fixed several reproducability bugs that led to different solving paths across multiple runs with one SCIP environment
1220- fixed check of limits/absgap, which was incorrectly applied to the scaled objective of the transformed problem
1221
1222Miscellaneous
1223-------------
1224
1225- in LP, use absolute instead of relative tolerances to check whether solutions from LP solver are primal feasible
1226- when a restart occurs, SCIP now asserts (during EXITSOLVE) that all relaxation-only variables are unlocked and
1227 only captured by the transformed problem.
1228- Avoid redundant calls to LP solver when LP is already flushed and solved
1229- In SCIPdebugMsg(), SCIPsetDebugMsg(), SCIPstatDebugMsg() strip directory from filename.
1230- Recompute activity of rows when checking LP solutions instead of trusting the value given by the LP solver
1231- The define NPARASCIP has been replaced by SCIP_THREADSAFE
1232- Parameters are not reset to their default values before activating an emphasis setting; this now allows to combine
1233 different emphasis settings.
1234- If a lazy bound is set to a value that is tighter than the current global bound, then the global bound is now tightened accordingly.
1235
1236Known bugs
1237----------
1238
1239@page RN70 Release notes for SCIP 7.0
1240
1241@section RN703 SCIP 7.0.3
1242*************************
1243
1244Interface changes
1245-----------------
1246
1247### New API functions
1248
1249- added function SCIPwithDebugSol() to determine whether SCIP was compiled with WITH_DEBUG_SOLUTION
1250
1251- New function SCIPcreateConsBounddisjunctionRedundant() and SCIPcreateConsBasicBounddisjunctionRedundant() that allow
1252 the input to contain redundant literals.
1253
1254### Changed API functions
1255
1256- added __attribute__((format(printf,,,))) to variadic SCIP message printing functions;
1257 this enables warnings about mismatches between format string and variadic function arguments if using GCC.
1258
1259### Interfaces to external software
1260
1261- removed MATLAB interface from interfaces/matlab
1262
1263Build system
1264------------
1265
1266- Compilation will now also work in a raw tarball of the scip git repository
1267
1268### Cmake
1269
1270- Make find_package more verbose and require packages to be found. Now enabled packages that are not found result in an error.
1271
1272Fixed bugs
1273----------
1274
1275- Fixed numerical bug by creating and checking the empty solution when problem vanishes in presolving.
1276- Fixed several bugs in reoptimization.
1277- Fixed bug in cons_bounddisjunction in which a constraint leads to a cutoff.
1278- Fixed bug in reoptimization by avoiding redundant literals for bound disjunctions.
1279- Replace wrong usage of CMAKE_BINARY_DIR by PROJECT_BINARY_DIR in CMake system
1280- Fixed lpi_glop to use absl flag instead of GFlags
1281- Fixed invalid initialization of limits/softtime parameter in cons_components
1282- Fixed MIN macro not defined in some cases.
1283- Safeguard some API methods for querying solving statistics against segmentation faults after SCIPpresolve()
1284- Fixed unfreed solution in concurrent solving
1285- Make sure that logicor constraints are enforced/separated if genlogicor is true in cons_indicator.
1286 Thus, do not change constraints/logicor/sepafreq anymore, but output warning.
1287- Fixed assert that assumed infeasibility cannot occur in presol_boundshift.
1288- Fixed sign bug during creation of conflict constraints with almost zero left-hand side.
1289- Disabled call of conflict handler for conflict sets that contain relaxation-only variables.
1290- Fixed bug in cons_symresack by initializing all constraint data in constrans
1291- Avoid allowing the upgrade of linear constraints corresponding to indicators in propagation of nodes.
1292- Fixed bug in computing lex. min/max faces in dynamic orbitope propagation.
1293- Limit vbounds propagator to one sweep through all bounds per call in order to avoid an infinite loop.
1294- Fixed mismatches between formatter strings and arguments in calls to SCIP message printing functions.
1295
1296Miscellaneous
1297-------------
1298
1299- To avoid performance variablity during reoptimization, the active constraints are now stored in the same order as in the
1300 original problem.
1301- Added workaround for bug in MSVS 2019 when compiling CppAD source.
1302- The original order of variables is now only restored after presolve if `randomization/permutevars` is set to FALSE.
1303
1304@section RN702 SCIP 7.0.2
1305*************************
1306
1307Features
1308--------
1309
1310- Extended check for valid variable and constraint names in PIP writer.
1311- Indicator constraints now write the name of the linear constraint in CIP format. This avoids a complicated
1312 name matching during parsing. The old format is still supported.
1313- The objective scale and offset are now taken into account when reading/writing problems in lp/mps/fzn/pip format.
1314 This often changes the behavior when writing transformed problems.
1315
1316Performance improvements
1317------------------------
1318
1319Examples and applications
1320-------------------------
1321
1322- Add c++ Sudoku example
1323
1324Interface changes
1325-----------------
1326
1327### New and changed callbacks
1328
1329### Deleted and changed API methods
1330
1331- deprecated SCIPsetParam(); use SCIPsetIntParam(), SCIPsetRealParam(), etc, instead
1332
1333### New API functions
1334
1335- new function SCIPcolGetVarProbindex() for accessing the probindex of a variable corresponding to a column
1336- added new sorting functions SCIPsortPtrRealRealBoolBool()
1337
1338### Command line interface
1339
1340### Interfaces to external software
1341
1342### Changed parameters
1343
1344### New parameters
1345
1346### Data structures
1347
1348Deleted files
1349-------------
1350
1351Unit tests
1352----------
1353
1354Testing
1355-------
1356
1357Build system
1358------------
1359
1360### Cmake
1361
1362### Makefile
1363
1364Fixed bugs
1365----------
1366
1367- Fixed a sign bug occuring for some cases in the computation of the directed cutoff distance
1368- Fixed overflow in inference information of cumulative constraint handler
1369- Fixed problem with propfreq == 0 in cons_linear.c
1370- Fixed aggregation heuristic in sepa_aggregation.c to not use local rows when that is requested nor modifiable rows
1371- Fixed problem with incompatibility of symmetry handling in Benders decomposition
1372- Fixed parsing of small number in CIP format of nonlinear constraint
1373- Fixed problem in upgrading full orbitopes to partitioning orbitopes
1374- Fixed treatment of negated variables in parsing orbitope constraints
1375- Fixed potential indexing error in prop_vbounds.c
1376- Fixed bug in writing fzn format
1377- Revert to old parameter value when parameter change is rejected in PARAMCHGD callback
1378- Fixed order of linker flags when building AMPL interface with cmake system.
1379- Fixed bug with ofsymcomptiming == 0: now symmetry is actually computed
1380- Improved separation for SOC constraint with multiaggregated variable on right-hand-side.
1381- Fixed bug in presol_boundshift: do not shift non-active variables
1382- Fixed bug in domain propagation for SOC constraints with negative coefficient for variable on right-hand-side.
1383- Fixed bug with multi-aggregated integer variables in cons_xor.
1384- Fixed bug with changed number of variables in storing relaxation solution in probing/diving.
1385- Fixed issues with scip statistics
1386- Fixed issue with multi-aggregated variables
1387- Fixed issue in with buffer memory in cons_cumulative
1388
1389Miscellaneous
1390-------------
1391
1392Known bugs
1393----------
1394
1395@section RN701 SCIP 7.0.1
1396*************************
1397
1398Build system
1399------------
1400
1401### Cmake
1402
1403- Fixed cmake module for Ipopt to support Ipopt 3.13
1404- Added cmake variable BLISS_LIBRARY_DIR to pass a bliss library
1405- Added warning to require minimal GCC version 4.8
1406- Renamed FindCriterion cmake findmodule to FindCRITERION
1407
1408### Makefile
1409
1410- Updated make/make.project for macOS
1411- Add SANITZERFLAGS (only OPT=dbg) to LDFLAGS also if SHARED=true (and rename SANITZERFLAGS to SANITIZERFLAGS)
1412- Fixed GCC version check in make/make.linux.gnu.dbg
1413
1414Fixed bugs
1415----------
1416
1417- Fixed handling of constant term in quadratic objective of pip-reader
1418- Fixed incorrect value string for parameter estimation/completiontype
1419- Fixed initialization of first LP which led to wrong output about LPs not resolved correctly
1420- Fixed bug in SCIPcutpoolClear() function not clearing internal datastructures properly
1421- Fixed inability to set a value in a solution if it was within epsilon to the current value
1422- Fixed problems for linking optimized code with debug library of SCIP (and vice versa) by moving debug-only members
1423 to end of SCIP structs
1424
1425Miscellaneous
1426-------------
1427
1428- Variables that are marked as relaxation-only are no longer checked against debug solutions if
1429 they are captured by the transformed problem only.
1430
1431@section RN700 SCIP 7.0.0
1432*************************
1433
1434Features
1435--------
1436
1437- Using the parameter "propagating/symmetry/recomputerestart" one can now decide to recompute symmetries after a
1438 restart or not. Previously one could just turn off symmetry computation after a restart. If orbital fixing
1439 has found a reduction before the restart occured, symmetries have to be updated to ensure correctness.
1440 To this end, the user can decide via "propagating/symmetry/disableofrestart" whether orbital fixing is disabled or
1441 whether symmetries are recomputed.
1442
1443- extended relaxators statistics in solve statistics about information on number of cutoffs, improved bounds, etc.
1444
1445- extends SMPS file reader for the stochastic information, the sto files, to read a lower bound for the discrete
1446 scenarios. The lower bound is used when creating the auxiliary variables for Benders' decomposition.
1447
1448- extended Benders framework to solve NLPs and generate optimality and feasibility cuts from their solution
1449 when the subproblem is convex nonlinear.
1450
1451- extended Benders framework to create copies of Benders decompositions that can be used in a multithreading environment
1452
1453- additional functionality has been added to enable the transfer of Benders' decomposition cuts between different SCIP
1454 instances, e.g., when used in UG
1455
1456- LP rows (SCIP_ROW) can now store pointer to a constraint from which the row originates
1457
1458- Trust region, a new LNS heuristic, has been added to SCIP as both a standalone primal heuristic heur_trustregion.c
1459 and as a neighborhood inside of Adaptive Large Neighborhood Search (heur_alns.c). This heuristic is designed to improve the
1460 heuristic performance of the Benders' decomposition algorithm. It builds upon the successful trust region approaches
1461 applied to Benders' decomposition.
1462
1463- Modularity of symmetry handling has been increased. It is now possible to use orbitopes (i.e., polyhedral symmetry
1464 handling techniques) and orbital fixing on the same instance.
1465
1466- cut strengthening enabled within the Benders' decomposition framework. This uses a mix of the Improved Magnanti-Wong
1467 method and Kelly's method. The cut strengthening is enabled by setting the paramemter
1468 "benders/<bendersname>/cutstrengthenenabled" to TRUE. The parameters "cutstrengthenmult", "noimprovelimit" and
1469 "corepointperturb" control the behavior of the cut strengthening method. Additionally, the parameter
1470 "cutstrengthenintpoint" allows the user to specify the solution that is used to initialize the core point. The options
1471 are the first LP solution, the first integer feasible solution, a relative interior point, a solution vector of all
1472 ones and a solution vector of all zeros. Also, the core point can be reinitialized after each update to the incumbent
1473 solution.
1474
1475- added option to adjust weights of different scores in relpscost (hybrid) branching rule based on degeneracy information
1476 and skip strong branching for very high degeneracy rates
1477
1478- added new SCIP_DECOMP* object to store user decompositions. The user can specify one or several decompositions by assigning variable
1479 and/or constraint labels either through the API or by reading a file in DEC format (which is one of the formats that GCG writes).
1480 This format specifies constraint labels, variable labels are inferred from that. The decomposition is transformed after presolving.
1481- statistics regarding the number of blocks, the largest and smallest blocks, the border, and the constraint graph are printed for the original decomposition,
1482 and for each decomposition after presolving.
1483- the decomposition can be used as initial decomposition for the Benders functionality of SCIP.
1484- new subsection "How to provide a problem decomposition" in the SCIP documentation
1485
1486- GINS heuristic can make use of a user-provided decomposition labels in two ways:
1487 1. by selecting a block of variables that maximizes the potential, and randomly selecting a start variable for the neighborhood and/or
1488 2. by selecting an interval of consecutive blocks as neighborhood, until fixing rate is reached. In this case, no variable is randomly selected.
1489
1490- extend potential parameter of GINS to allow computation based on local LP solution, as well
1491
1492- new primal heuristic Adaptive Diving, which registers all publicly available dive sets from other diving heuristics.
1493 At each call, it selects one of the available dive sets based on the user's score type choice (heuristics/adaptivediving/scoretype).
1494 During the solution process, the heuristics learns online which divesets reach the best score, and executes them more frequently.
1495 The statistic output for Diving heuristics has been extended to incorporate the statistics of each dive set within Adaptive diving.
1496
1497- Added new penalty alternating direction method (PADM) primal heuristic that splits the problem into several sub-SCIPs
1498 according to a user-provided decomposition. The sub-SCIPs are solved on an alternating basis until a feasible solution of
1499 the original problem is found.
1500
1501- Symmetry handling constraints (cons_orbisack, cons_orbitope, cons_symresack) now have an additional parameter to encode
1502 whether they are model constraints, i.e., define the problem, or whether they are only present to handle symmetries.
1503
1504- The symmetry code has been completely restructured. The presolvers presol_symbreak and presol_symmetry as well as the propagator
1505 prop_orbitalfixing have been merged into the single propagator prop_symmetry to avoid storing the same information
1506 multiple times. This propagator is now responsible for adding symmetry handling constraints as well as activating orbital
1507 fixing. Moreover, the new file symmetry.c contains general functions for symmetry computations like orbit computations.
1508
1509- Variables can now be marked as "relaxation-only". This flag should be used to introduce new variables that are required
1510 to define a relaxation, but that are not part of any checked constraints. Essentially, these variables should only be used
1511 in the current SCIP solve and disregarded after a restart or in SCIP copies. Hence, these variables are not copied by SCIPcopy and
1512 SCIPgetVarCopy, they are currently not used in conflict constraints, and cuts involving them are not upgraded to linear constraints.
1513 Relaxation-only variables cannot appear in the objective function.
1514
1515- The OSiL reader now supports nonlinear expressions of type "signpower".
1516
1517- Expressions of form abs(x)^p * x in a nonlinear constraint are now sometimes recognized and handled by abspower constraints.
1518
1519- If polyhedral symmetry handling methods are used (cons_orbisack, cons_orbitope, cons_symresack), it is now possible to
1520 recompute symmetries if a restart occured.
1521
1522- upgrade some more quadratic constraints to second-order cone constraints, that is,
1523 handle linear binary variables as if squared in simple upgrade and
1524 do not require bounds for variables that have a zero entry in the computed eigenvectors in the non-simple upgrade
1525
1526- new variable event when changing the variable type
1527
1528- It is no longer necessary to provide a SCIP pointer for the subproblem in SCIPaddBendersSubproblem if custom solving
1529 methods are defined. A NULL pointer can be supplied to SCIPaddBendersSubproblem. In this case, no internal Benders'
1530 cut generation methods can be used.
1531
1532- Using the parameter "constraints/symresack/checkmonotonicity" one can now decide to upgrade to packing/partitioning
1533 symresacks even if the underlying permutation is not monotone.
1534
1535- New branching rule `vanillafullstrong`, mostly for scientific purpose, with the following features:
1536 1) no cutoff or domain reduction: only branching;
1537 2) idempotent (optional): leave SCIP, as much as possible, in the same state before / after the strong branching calls
1538 - basically, do not update any statistic;
1539 3) donotbranch (optional): do no perform branching. So that the brancher can be called as an oracle only
1540 (on which variable would you branch ? But do not branch please);
1541 4) scoreall (optional): keep scoring variables, even if infeasibility is detected;
1542 5) collectscores (optional): store the candidate scores from the last call, which can then be retrieved by calling SCIPgetVanillafullstrongData();
1543 6) integralcands (optional): consider integral candidates for branching,
1544 i.e., get candidates from SCIPgetPseudoBranchCands() instead of SCIPgetLPBranchCands().
1545
1546- If a reference value (misc/referencevalue) is given, the primal-reference and reference-dual integrals are calculated automatically and printed within the SCIP statistics.
1547
1548- Locally valid cuts / rows are now considered for dual proof analysis when `conflict/uselocalrows` is set to TRUE.
1549
1550- Linking variables in the linking constraint handler (cons_linking.{ch}) can now be integer or continuous. The coefficients of the binary variables are therefore now stored as SCIP_Real.
1551
1552- To save memory, it is now possible to remove all variables from the internal symmetry data structures that are
1553 not affected by any symmetry.
1554
1555- Allow to filter first variables from orbits and transfer pseudo cost information to variables in orbit
1556
1557- Add integration of external MILP presolve library as a SCIP presolver plugin that runs on MILP problems
1558
1559- Parallelisation can be used when applying Benders' decomposition. There are two different forms of parallelisation
1560 available. The first is applying Benders' decomposition within a parallel branch-and-bound. This is achieved through
1561 the integration with the UG framework. The second is the use of shared memory parallelisation for solving the Benders'
1562 decomposition subproblems. A priority queue has been added to help with load balancing.
1563
1564- The Benders' decomposition framework can handle MINLPs. If a convex relaxation of the MINLP exists, then this is
1565 solved to generate optimality and feasibility cuts. The extensions to the framework are:
1566 - New generic solving methods to solve convex NLP subproblems.
1567 - Modification to benderscut_opt and benderscut_feas to enable the generation of cuts from convex NLPs.
1568 - Addition of benderscut_feasalt to generate feasibility cuts from an alternative subproblem that minimises the
1569 violation of infeasible problems.
1570 - Better handling of subproblem solution results
1571
1572- Adds a feasibility phase to the Benders' decomposition subproblem solving methods. The feasibility phase adds slack
1573 variables to each of the constraints to ensure feasibility of the subproblem. A large coefficient is given to these
1574 slack variables in the objective function to penalise constraint violations. The coefficients are progressively
1575 increased until all slack variables take the value 0.0.
1576
1577- Improved convexity check for Benders' decomposition subproblems. The constraints of the subproblem are now checked for
1578 convexity in the initialisation of the Benders' decomposition algorithm. This enables the solving of convex NLPs as
1579 Benders' decomposition subproblems.
1580
1581- Benders' decomposition can be applied using decomposition supplied in the DEC format. To apply Benders' decomposition
1582 the parameters decomposition/benderslabels and decomposition/applybenders must be set to TRUE.
1583
1584- new event handler event_estim.c/h that approximates search tree completion and estimates tree size
1585 to trigger restarts; many approximations of search tree completion and estimation, including WBE, SSG, and tree profile method
1586- new display column that reports approx. search tree completion during the search, and an overview in the statistics table
1587- added resources (script, tutorial, test data) to adapt tree size estimation to user instances.
1588
1589- Orbital Fixing uses a list of variables that have been fixed globally since the computation of symmetries to filter
1590 symmetries. Previously, some plugins were disabled, which is not necessary anymore.
1591
1592- A new presolver "dualsparsify" was added. It tries to combine columns (i.e. variables) to cancel nonzero coefficients in the constraint matrix.
1593
1594- The presolver "tworowbnd" was implemented with better performance.
1595
1596- To be able to calculate better bounds for the dual variables, the presolver "dualinfer" was extended by the ability to perform convex combinations of continuous columns.
1597
1598- allow disabling of pricers during solving process
1599
1600- added emphasis setting for numerically challenging instances
1601
1602Performance improvements
1603------------------------
1604
1605- Extended cut presolving by removing variables that been fixed at their bounds
1606
1607- Improved branching point selection when branching on externals branching candidates. Instead of using exactly the
1608 LP solution, a point closer to the middle of the variables domain is chosen.
1609
1610- Matrix presolvers that do not work on incomplete matrices now skip matrix creation if unsupported constraint types are detected.
1611
1612- consLockBenders callback implemented to add down locks on the Benders' decomposition auxiliary variables and
1613 up and down locks per subproblem for all master problem variables. This allows the use of presolving and propagation
1614 with Benders' decomposition.
1615
1616- improved performance of orbital fixing in several ways:
1617 store permutations in transposed form to improve cache efficency;
1618 reverse order to speed up filtering of permutations;
1619 handle variables globally fixed to 1 in list;
1620 use event handler to catch global fixings;
1621 speed up orbit computations;
1622 change handling of restarts;
1623 use only permutations that can contribute to a variable's orbit;
1624
1625- allow rapid learning at local nodes
1626
1627- allow to recompute cut without using fractional values for sepa_cgmip
1628
1629- restrict the number of the clique table nonzeros relative to the number of problem nonzeros, which could be a performance bottleneck.
1630
1631- variable fixings of LP face heuristic are now computed earlier; subproblem creation is skipped if not enough variables are fixed.
1632
1633- Improved domcol presolver to not require a complete representation of all constraints in the matrix
1634
1635- performance improvement of adaptive large neighborhood search heuristic on merely continuous problems. The heuristic
1636 stops if presolving in the sub-SCIP fixes less than 50 % of the current target fixing rate over all variables
1637 (including continuous).
1638
1639- reduce memory usage in symmetry detection by a staggered allocation with decreasing overhead for larger instances
1640
1641- improved full orbitope propagation using a static implementation or a dynamic reordering of orbitope rows by a global rank function
1642
1643- improved detection of packing/partitioning orbitopes
1644
1645- enable an in-tree restart if after a reasonable initialization, the estimated size of the remaining tree is large.
1646
1647
1648Examples and applications
1649-------------------------
1650
1651- added methods to set and get hmin and hmax for optcumulative constraints
1652
1653Interface changes
1654-----------------
1655
1656### New and changed callbacks
1657
1658- new optional callback `SCIP_DECL_DIVESETAVAILABLE` to check preconditions for this dive set, e.g., if an incumbent solution is available,
1659 which is passed as new argument to SCIPcreateDiveset(). SCIPcreateDiveset() has another new parameter "ispublic".
1660
1661- new callback `SCIP_DECL_CONSHDLRCOPY` and `SCIP_DECL_CONSCOPY` in cons_orbisack and cons_symresack
1662
1663- new `idempotent` argument to SCIPgetVarStrongbranchInt() and SCIPgetVarStrongbranchFrac(),
1664 so that statistics are not updated during the call. Likewise, new `updatecol` and `updatestat` arguments to SCIPcolGetStrongbranch().
1665
1666- callback `SCIP_DECL_CONSHDLRENFOLP` can now also return SCIP_SOLVELP as *result, which indicates to the SCIP core that the LP relaxation
1667 should be solved again because the primal feasibility tolerance of the LP has been tightened (using SCIPsetLPFeastol())
1668
1669- extension of SCIP_PQUEUE by a new callback SCIP_DECL_PQUEUEELEMCHGPOS to catch swaps as well as functionality to delete arbitrary elements from the priority queue.
1670
1671### Deleted and changed API methods
1672
1673- LPI:
1674 + now for all lp interfaces consistent requirements on SCIP_LPPAR:
1675 LPITLIM and BARRIERCONVTOL positive or zero; FEASTOL, DUALFEASTOL, LPTILIM strictly positive
1676 + now projecting SCIP_LPPAR values on feasible values for each lp interface
1677 + add interface to Glop
1678 + fixed mapping between scaling parameter values in Gurobi LPI lpi_grb
1679- Symmetry:
1680 + removed method SCIPseparateCoversOrbisack() in cons_orbisack.h since the orbitope constraint
1681 handler has its own implementation of this routine with advanced features now
1682 + renamed SCIPgetGeneratorsSymmetry() to SCIPgetSymmetry() and removed two arguments
1683 + extended method SCIPgetSymmetry(): It is possible to access both the original and
1684 transposed permutations matrix as well as the (independent symmetry) components of a permutation group now.
1685 + arguments of functions SCIPcreateConsOrbisack(), SCIPcreateConsBasicOrbisack(), SCIPcreateConsOrbitope(),
1686 SCIPcreateConsBasicOrbitope(), SCIPcreateConsSymresack(), SCIPcreateConsBasicSymresack(), and SCIPcreateSymbreakCons() extended
1687 by "ismodelcons" to encode whether the constraints are model constraints or not
1688 + the function SCIPgetSymmetry() no longer accepts the parameter recompute, but has parameter permvarmap as new input
1689 + removed SCIPgetPermvarsObjSymmetry(), SCIPsetSymmetryComponentblocked(), SCIPgetSymmetryComponentblocked(),
1690 SCIPgetSyminfoGloballyFixedVars(), SCIPcomputeGroupOrbitsSymbreak, SCIPincludePresolSymmetry(),SCIPincludePresolSymbreak(),
1691 and SCIPincludePropOrbitalfixing()
1692 + add function SCIPcomputeOrbitsComponentsSym() to compute orbits without filtering permutations and indices of orbits for each variable
1693- SCIPallowObjProp() and SCIPallowDualReds() are deprecated and replaced by SCIPallowWeakDualReds() and SCIPallowStrongDualReds(), respectively
1694- Benders' decomposition
1695 + changed SCIPstoreBenderscutCut() in scip_benders.c to SCIPstoreBendersCut(). Where this function used to take a
1696 SCIP_BENDERSCUT pointer, it now accepts a SCIP_BENDERS pointer.
1697 + the functions SCIPsolveBendersSubproblem() no longer accepts the parameter type. The type is not a necessary
1698 argument for the subproblem solving method.
1699 + arguments of functions SCIPbendersSolveSubproblemLP(), SCIPbendersSolveSubproblemCIP(), and SCIPbendersOnlyCheckConvexRelax() changed
1700 - removed SCIPbenderscutGetNAddedCuts() and SCIPbenderscutGetAddedCutData()
1701
1702
1703### New API functions
1704
1705- new argument "onlyifcomplete" in SCIPmatrixCreate() to skip matrix creation right after detecting unsupported constraint types
1706 and new arguments to count statistics when doing a clean-up of inactive variables in the constraints before building the matrix
1707
1708- new argument "threadsafe" in SCIPcopy(), SCIPcopyConsCompression(), SCIPcopyOrig(), SCIPcopyOrigConsCompression and
1709 SCIPcopyBenders(). This argument must only be set to TRUE if the source and target SCIP instances are to be solved in
1710 parallel. Setting this argument to TRUE has a performance cost.
1711
1712- new argument "append" in SCIPsetModifiedDefaultSettingsIpopt()
1713- functions SCIPclearRelaxSolVals(), SCIPsetRelaxSolVal(), SCIPsetRelaxSolVals(), SCIPsetRelaxSolValsSol(), and SCIPmarkRelaxSolValid()
1714 receive an additional argument "relax" to store the relaxation handler as creator of the relaxation solution.
1715
1716- LP:
1717 - SCIProwGetOriginCons() now returns a SCIP_CONS* instead of a SCIP_CONSHDLR*, use SCIProwGetOriginConshdlr() for the previous behavior
1718 - SCIPcreateRowCons() and SCIPcreateEmptyRowCons() now expect a SCIP_CONS* instead of a SCIP_CONSHDLR*,
1719 use SCIPcreateRowConshdlr() and SCIPcreateEmptyRowConshdlr(), respectively, for the previous behavior
1720 - deprecated SCIPlpfeastol() and SCIPchgLpfeastol(), use SCIPgetLPFeastol() and SCIPsetLPFeastol()
1721
1722- new parameter "divecontext" for every method that queries statistics for a diveset. The context can be used to distinguish between the dive set
1723 as single (standalone) heuristic or within Adaptive Diving.
1724- new parameters "divecontext" and "iterlim" to SCIPperformGenericDivingAlgorithm() to control in which context (single,adaptive) statistics are updated.
1725
1726- SCIPcopyVars, SCIPcopy, SCIPcopyConsCompression, and SCIPgetVarCopy do not copy variables that are marked as relaxation-only,
1727 thus it cannot be assumed anymore that each active variable from the master SCIP also has a counterpart in the copy.
1728 SCIPcopy, SCIPcopyConsCompression, and SCIPcopyConss can now return *valid=TRUE if some non-checked and non-enforced constraints were not copied, e.g.,
1729 because they involved relaxation-only variables. Thus, a copy is already regarded as valid if all checked or enforced constraints were copied successfully.
1730
1731- linking constraint handler:
1732 - changed type of vals argument from int* to SCIP_Real* in SCIPcreateConsLinking() and SCIPcreateConsBasicLinking()
1733 - SCIPgetIntvarLinking() has been renamed to SCIPgetLinkvarLinking().
1734 - changed return value of SCIPgetValsLinking() from int* to SCIP_Real*.
1735 - new method SCIPgetBinvarsDataLinking().
1736
1737- SCIPbendersCheckSubproblemOptimality() now returns a boolean indicating whether the subproblem is optimal or not.
1738 Previously this result was returned through a parameter. The change was required to facilitate the integration with
1739 the UG framework.
1740
1741- deleted SCIPcombineTwoInt(), SCIPcombineThreeInt(), SCIPcombineFourInt(); use the appropriate SCIPhashTwo(), ..., SCIPhashSeven() method instead
1742
1743- SCIPsetupBendersSubproblem takes a parameter of the enforcement type.
1744
1745- SCIPcreateNlpiProb takes a hashmap to store the map between the nlrows and the index in the nlrow array.
1746
1747### New API functions
1748
1749- SCIPallowWeakDualReds() and SCIPallowStrongDualReds() replace the deprecated SCIPallowObjProp() and SCIPallowDualReds(), respectively
1750- methods have been added to facilitate the transfer of Benders' decomposition cuts between solvers in UG. These include
1751 SCIPapplyBendersStoredCuts(), SCIPbendersGetNStoredCuts(), SCIPbendersGetStoredCutData() and
1752 SCIPbendersGetStoredCutOrigData().
1753- added SCIPisConvexAbspower()
1754- new functions SCIPsolGetType(), SCIPsolGetRelax(), SCIPsolSetRelax(), SCIPsolSetLPRelaxation(), SCIPsolSetStrongbranch(),
1755 SCIPsolSetPseudo to set or query the new type attribute of a primal solution. The type attribute gives information
1756 about the origin of the solution, ie, whether it was created by a relaxation handler,
1757 by the LP relaxation, by strong branching, by the current pseudo solution, or by a primal heuristic.
1758 The meaning of the argument 'heur' in all creation methods for primal solutions such as SCIPcreateSol() stays unchanged.
1759- added SCIProwGetOriginConshdlr(), SCIPcreateRowConshdlr(), SCIPcreateEmptyRowConshdlr()
1760- new API functions SCIPsetCommonSubscipParams(), SCIPtranslateSubSol(), and SCIPtranslateSubSols() shared by several Large Neighborhood Search heuristics.
1761- new API function SCIPgetLPDualDegeneracy() to get two measures for the dual degeneracy of the current LP
1762- new API functions SCIPdivesetIsAvailable() to check preconditions of a dive set and SCIPdivesetIsPublic() to check if the dive set can be used
1763 by other primal heuristics.
1764- new API functions SCIPcomputeOrbitsSym(), SCIPcomputeOrbitsFilterSym(), SCIPgetPropertiesPerm(), SCIPdetermineBinvarAffectedSym(),
1765 SCIPdetermineNVarsAffectedSym(), SCIPcomputeComponentsSym(), and SCIPextendSubOrbitope(), SCIPgenerateOrbitopeVarsMatrix() for symmetry computations
1766- new API functions SCIPvarIsRelaxationOnly() and SCIPvarMarkRelaxationOnly() to query and set, resp., whether a variable is marked as relaxation-only
1767- new API functions SCIPconshdlrGetNUpdateConss() and SCIPconshdlrGetUpdateConss(), for expert users only
1768- new API function SCIPgetNConflictDualproofsApplied()
1769- new API functions SCIPeventGetOldtype() and SCIPeventGetNewtype() for the new event when changing the variable type
1770- new API function SCIPisConvexConsQuadratic() to check whether a quadratic constraint is convex when a given set of variables would be fixed
1771- new API functions SCIPgetLPFeastol(), SCIPsetLPFeastol(), and SCIPresetLPFeastol() to get, set, and reset (to the default), respectively, the primal
1772 feasibility tolerance for the LP relaxation
1773- new API functions SCIPcleanupConss{Linear,Varbound,Setppc,Logicor,Knapsack}() to clean up inactive variables from those types of linear constraints
1774- new API function SCIPsetBendersSubproblemComp() used to add a custom comparison method for ordering the Benders'
1775 decomposition subproblem solves. The comparison method is used to help with load balancing.
1776- new API function SCIPgetRowObjParallelism to get the objective parallelism of a row
1777- new API function SCIPcolGetAge to get the age of a column
1778- added SCIPhashThree(), SCIPhashFive(), SCIPhashSix(), and SCIPhashSeven() that complement SCIPhashTwo(), SCIPhashFour() to combine 32bit integers to
1779 a 32bit hash value
1780- new API function SCIPgenerateAndApplyBendersOptCut is used to generate a Benders' optimality cut using the dual
1781 solutions. This function can be supplied vectors for the primal and dual solution for generating an optimality cut.
1782 This avoids the need for a SCIP instance to solve the Benders' decomposition subproblem and generating cuts.
1783- new API function SCIPconsAddCoef used for adding a coefficient to a linear-type constraint.
1784- new API functions SCIPconsNonlinearGetRhs, SCIPconsNonlinearGetLhs and SCIPconsNonlinearAddLinearCoef for getting the
1785 RHS and LHS from a nonlinear-type constraint and adding a linear coefficient to the constraint.
1786- new API function SCIPbendersSolSlackVarsActive for checking whether any slack variables from the feasibility phase are
1787 active in the subproblem solution.
1788- new API functions SCIPbendersSetSubproblemType and SCIPbendersGetSubproblemType sets and gets the subproblem type.
1789 This is either:
1790 - Convex constraints with continuous variables
1791 - Convex constraints with discrete variables
1792 - Non-convex constraints with continuous variables
1793 - Non-convex constraints with discrete variables
1794- new API functions SCIPbendersSetSubproblemIsNonlinear() and SCIPbendersSubproblemIsNonlinear() for setting and
1795 identifying whether the Benders' decomposition subproblems contain nonlinear constraints. Similarly, the functions
1796 SCIPbendersSetMasterIsNonlinear() and SCIPbendersMasterIsNonlinear() sets and identifies whether the Benders'
1797 decomposition master problem contains nonlinear constraints.
1798- new API function SCIPapplyBendersDecomposition for applying Benders' decomposition given a decomposition in the DEC
1799 format
1800- new API function SCIPwasNodeLastBranchParent to query if a node has been the parent of the most recent branching in the tree
1801- new API functions SCIPtreemodelInit(), SCIPtreemodelFree(), SCIPtreemodelIsEnabled(), SCIPtreemodelSelectCandidate() related to the new
1802 treemodel way of comparing branching candidates. These functions are only currently used for reliability pscost branching, but they can be used
1803 in other parts of the code.
1804- New function SCIPcalcChildEstimateIncrease() to compute the increase in the child estimation
1805- new API functions SCIPisOrbitalfixingEnabled() and SCIPgetSymmetryNGenerators() to check whether orbital fixing is
1806 enabled and to get the number of generators of the current symmetry group, respectively
1807- new API function SCIPdelNlRow() to remove a row from the NLP
1808
1809### Event system
1810
1811- new event type SCIP_EVENTTYPE_NODEDELETE to react on nodes that are about to be deleted from the tree
1812
1813### Changed parameters
1814
1815- renamed parameter "propagating/orbitalfixing/enableafterrestart" to ".../symmetry/recomputerestart"
1816- Parameter "misc/allowdualreds" is now called "misc/allowstrongdualreds"
1817- Parameter "misc/allowobjprop" is now called "misc/allowweakdualreds"
1818- changed default values of propagation (new value: 1, old value: 5) and separation frequency (new value: -1, old value: 5) in cons_orbitope.c
1819- all primal heuristics that use sub-SCIPs are disabled within the heuristics fast emphasis setting
1820- deleted parameter heuristics/localbranching/useuct, use heuristics/useuctsubscip instead
1821- changed default value of "presolving/symbreak/detectorbitopes" (new value: TRUE, old value: FALSE)
1822- extended range of "misc/usesymmetry" (new range: [0,3], old range: [0,2])
1823- deleted parameter "constraints/orbisack/checkalwaysfeas"
1824- deleted parameter "constraints/orbitope/checkalwaysfeas"
1825- deleted parameter "constraints/symresack/checkalwaysfeas"
1826- deleted parameter "presolving/symmetry/maxgenerators"
1827- deleted parameter "presolving/symmetry/checksymmetries"
1828- deleted parameter "presolving/symmetry/displaynorbitvars"
1829- deleted parameter "presolving/symbreak/conssaddlp"
1830- deleted parameter "presolving/symbreak/addsymresacks"
1831- deleted parameter "presolving/symbreak/computeorbits"
1832- deleted parameter "presolving/symbreak/detectorbitopes"
1833- deleted parameter "presolving/symbreak/addconsstiming"
1834- deleted parameter "propagating/orbitalfixing/symcomptiming"
1835- deleted parameter "propagating/orbitalfixing/performpresolving"
1836- deleted parameter "propagating/orbitalfixing/recomputerestart"
1837- changed default value of "heuristics/coefdiving/freq" (old: 10, new: -1)
1838- changed default value of "heuristics/conflictdiving/freq" (old: -1, new: 10)
1839- changed default value of "heuristics/conflictdiving/lockweight" (old: 1.0, new: 0.75)
1840- replaced parameter "numerics/lpfeastol" by "numerics/lpfeastolfactor" to specify which factor should be applied to the SCIP feasibility
1841 tolerance to initialize the primal feasibility tolerance of the LP solver
1842- enabling aggressive presolving now activates all available presolving plugins,
1843 and decreases the presolving/restartfac parameter correctly with respect to default.
1844- changed default value of heuristics/rins/nodesquot to 0.3 (was 0.1), to compensate
1845 the removal of a hard coded factor of 3.0 in the code without affecting the default behavior
1846 of the RINS heuristic.
1847- changed default value of "constraints/quadratic/empathy4and" (old: 0, new: 2)
1848- changed default value of "propagating/redcost/useimplics" (old: TRUE, new: FALSE)
1849
1850### New parameters
1851
1852- the possibility to define the Benders' decomposition auxiliary variables as implicit integer is provided. This
1853 behavior is controlled with an additional parameter in the Benders' decomposition framework.
1854- added parameter benders/<bendersname>/cutcheck to enable the generation of Benders' decomposition cuts during solution
1855 checking.
1856- constraints/orbitope/usedynamicprop: the possibility to propagate orbitope constraints by reordering the rows based on the
1857 branching strategy is provided (only possible for non-model constraints)
1858
1859- new parameters heuristics/shiftandpropagate/minfixingratelp and heuristics/locks/minfixingratelp to stop the
1860 heuristics after propagating integer fixings if no sufficient fixing of the all variables (including continuous)
1861 could be achieved. These parameters help to avoid solving LP's that are comparable in hardness to the main root LP.
1862
1863- Added parameters branching/midpull and branching/midpullreldomtrig to control by how much to move
1864 the branching point for an external branching candidate closer to the middle of the candidates domain. The
1865 default of 0.75 and 0.5, respectively, uses a point that is 75*alpha% closer to the middle of the domain, where
1866 alpha is the relative width of the candidates domain (width of local domain divided by width of global domain),
1867 if the latter is below 0.5, and alpha=1.0 otherwise. That is, with the default settings, a branching point is
1868 chosen closer to the middle of the candidates domain if the variables local domain is still similar to its
1869 global domain, but is chosen closer to the LP solution if the local domain is much smaller than the global
1870 domain.
1871
1872- Added parameter lp/minmarkowitz to set the Markowitz stability threshold (range 0.0001 to 0.9999).
1873 High values sacrifice performance for stability.
1874
1875- Added parameters benders/<bendersname>/lnsmaxcalls and benders/<bendersname>/lnsmaxcallsroot to the Benders'
1876 decomposition core. These parameters limit the number of Benders' decomposition subproblem checks, for the full
1877 branch-and-bound tree and root node respective, when solving the auxiliary problem of LNS hueristics. These
1878 parameters only have effect if the lnscheck parameter is set to TRUE.
1879
1880- Added parameter cons/linear/maxmultaggrquot to limit the maximum coefficient dynamism of an equation on which
1881 multiaggregation is performed. This replaces a compiler define of the same name.
1882 Default value is 1000, smaller values make multiaggregations numerically more stable.
1883- new global parameter heuristics/useuctsubscip that affects all LNS heuristics using common sub-SCIP parameters
1884
1885- new parameter branching/relpscost/degeneracyaware to switch degeneracy-aware hybrid branching
1886
1887- new parameter separation/rapidlearning/checkexec to check whether rapid learning is allowed to run locally
1888- new parameters separation/rapidlearning/check{degeneracy,dualbound,leaves,nsols,obj} to enable checking the respective feature for local rapid learning
1889- new parameter separation/rapidlearning/maxcalls to limit the number of rapid learning executions
1890- new parameter separation/rapidlearning/nwaitingnodes to set the number of waiting nodes before the dual bound is checked
1891- new parameter separation/rapidlearning/mindegeneracy to set the minimal threshold of degenerate basic-variables
1892- new parameters separation/rapidlearning/minvarconsratio to set the minimal ratio of unfixed variables in relation to basis size
1893
1894- new parameters to control the Benders' decomposition two-phase method.
1895 - constraints/benderslp/depthfreq: after the maxdepth is reached, then the two-phase method will only be called at
1896 nodes at a depth divisible by depthfreq.
1897 - constraints/benderslp/stalllimit: after the maxdepth is reached, if there has been no improvement in the dual bound
1898 for stalllimit number of nodes, then the two-phase method is executed for the next fractional LP solution that is
1899 encountered.
1900 - constraints/benderslp/iterlimit: after the root node, only iterlimit fractional LP solutions are used at each node
1901 to generate Benders' decomposition cuts.
1902
1903- new parameters for symmetry handling
1904 - new parameter "propagating/symmetry/maxgenerators"
1905 - new parameter "propagating/symmetry/checksymmetries"
1906 - new parameter "propagating/symmetry/displaynorbitvars"
1907 - new parameter "propagating/symmetry/conssaddlp"
1908 - new parameter "propagating/symmetry/addsymresacks"
1909 - new parameter "propagating/symmetry/detectorbitopes"
1910 - new parameter "propagating/symmetry/addconsstiming"
1911 - new parameter "propagating/symmetry/ofsymcomptiming"
1912 - new parameter "propagating/symmetry/performpresolving"
1913 - new parameter "propagating/symmetry/recomputerestart"
1914 - new parameter "constraints/symresack/checkmonotonicity"
1915 - new parameter "propagating/symmetry/compresssymmetries"
1916 - new parameter "propagating/symmetry/compressthreshold"
1917 - new parameter "propagating/symmetry/disableofrestart"
1918 - new parameter "propagating/symmetry/symfixnonbinaryvars"
1919
1920- new parameter for enabling shared memory parallelisation for solving Benders' decomposition subproblems. The parameter
1921 benders/<bendersname>/numthreads sets the number of threads used for parallel subproblem solving.
1922
1923- new parameters to control enhancements for solving MINLPs by Benders' decomposition
1924 - benders/<bendersname>/execfeasphase: enables the feasibility phase for solving the Benders' decomposition
1925 subproblems
1926 - benders/<bendersname>/slackvarcoef: the initial coefficient of the slack variable for the feasibility phase
1927 - benders/<bendersname>/checkconsconvexity: should the constraints be checked for convexity. This can be set to FALSE
1928 if you are certain that the NLP subproblem is convex.
1929
1930- new parameter presolving/clqtablefac (default value 2.0) as limit on number of entries in clique table relative to number of problem nonzeros
1931
1932- new parameter conflict/uselocalrows (default: TRUE) to incorporate locally valid cuts / rows for dual proof analysis
1933
1934- new return code SCIP_NOTIMPLEMENTED for functions, e.g., in the LPI that have not been implemented (yet)
1935
1936- new parameter separating/cgmip/genprimalsols that allows to generate initial primal solutions from Gomory cuts
1937
1938- new parameter branching/relpscost/filtercandssym to allow filtering from orbits
1939
1940- new parameter branching/relpscost/transsympscost to transfer pseudo cost information to orbit
1941
1942- new parameters for tree size estimation and restarts:
1943 - estimation/restarts/restartpolicy (default value n)
1944 - estimation/method (default value c)
1945 - estimation/restarts/restartlimit (default value 1)
1946 - estimation/restarts/minnodes (default value 1000)
1947 - estimation/restarts/countonlyleaves (default value FALSE)
1948 - estimation/restarts/restartfactor (default value 2)
1949 - estimation/coefmonoprog (default value 0.3667)
1950 - estimation/coefmonossg (default value 0.6333)
1951 - estimation/restarts/hitcounterlim (default value 50)
1952 - estimation/reportfreq (default value -1)
1953 - estimation/regforestfilename (default value "-")
1954 - estimation/completiontype (default value a)
1955 - estimation/treeprofile/enabled (default value FALSE)
1956 - estimation/treeprofile/minnodesperdepth (default value 20)
1957 - estimation/useleafts (default value TRUE)
1958 - estimation/ssg/nmaxsubtrees (default value -1)
1959 - estimation/ssg/nminnodeslastsplit (default value 0)
1960
1961- new parameter constraints/linear/extractcliques to turn clique extraction off
1962
1963- new emphasis setting emphasis/numerics to increase numerical stability of (mostly) presolving operations such as (multi-)aggregations at the cost of performance.
1964
1965- new parameters for treemodel:
1966 - new parameter branching/treemodel/enable to enable the treemodel in reliability pscost branching and possible
1967 future parts of the code where it could be used.
1968 - new parameter branching/treemodel/highrule to specify which branching rule to use when treemodel thinks the node
1969 is high in the tree.
1970 - new parameter branching/treemodel/lowrule to specify which branching rule to use when treemodel thinks the node
1971 is low in the tree.
1972 - new parameter branching/treemodel/height to specify at which (estimated) height a node is high or low in the tree.
1973 - new parameter branching/treemodel/filterhigh to specify whether to filter dominated candidates in nodes which are
1974 high in the tree.
1975 - new parameter branching/treemodel/filterlow to specify whether to filter dominated candidates in nodes which are
1976 low in the tree.
1977 - new parameter branching/treemodel/maxfpiter to specify the maximum number of fixed-point iterations to use when
1978 computing the ratio of a variable using the fixed-point method.
1979 - new parameter branching/treemodel/maxsvtsheight to specify the maximum height to compute the SVTS score exactly
1980 before approximating it using the ratio.
1981 - new parameter branching/treemodel/fallbackinf defines the fallback strategy to use when the tree size estimates
1982 obtained by SVTS are infinite.
1983 - new parameter branching/treemodel/fallbacknoprim defines the fallback strategy to use when no primal bound is known
1984 and thus SVTS would not be able to compute a tree size (it would be infinite).
1985 - new parameter branching/treemodel/smallpscost defines the value under which pscosts are considered too small to be
1986 the deciding factor for branching, in which case it may be better not to use the treemodel.
1987
1988- new parameters for symmetry handling constraint handlers to enforce that also non-model constraint are copied:
1989 - new parameter "constraints/orbisack/forceconscopy"
1990 - new parameter "constraints/orbitope/forceconscopy"
1991 - new parameter "constraints/symresack/forceconscopy"
1992
1993
1994### Data structures
1995
1996- small changes in constants of hash functions
1997- added fast 2-universal hash functions for two to seven 32bit elements with 32bit output
1998- extended SCIPpqueueCreate() by additional callback argument SCIP_DECL_PQUEUEELEMCHGPOS to catch position changes
1999- new methods SCIPpqueueDelPos() to delete elements at a specific position in the priority queue and SCIPpqueueFind() to
2000 find a specific position. It is recommended to track position changes using the new callback SCIP_DECL_PQUEUEELEMCHGPOS.
2001 In contrast, using SCIPpqueueFind() can be slow because it needs to compare the element it searches for
2002 with each slot in the queue.
2003
2004### Build system
2005
2006- The default value for DFLAGS in the non-cmake buildsystem has changed from -MM to -MMD. This will break the
2007 generation of depend.* files if that was done by a compiler call that relied on -MM. The new preferred way
2008 to handle compilation dependencies is to additionally use $(DFLAGS) when compiling the object files (.o) and
2009 to include the generated .d files in the Makefile, see also "Build system / Makefile" below.
2010
2011Unit tests
2012----------
2013 - new unit test for treemodel.
2014
2015Testing
2016-------
2017
2018 - fixed an issue that may have lead to wrong status reports in the evaluation scripts
2019
2020Build system
2021------------
2022
2023### Cmake
2024
2025- avoid problem with doubly defined object together with CPLEX
2026
2027### Makefile
2028
2029- Removed static object compilation dependency files (depend.*). If using a GCC compatible compiler, then dependency
2030 files are now dynamically created and updated during build. The new dependency files (*.d) reside next to each object
2031 file (.o) in the corresponding obj subdirectory.
2032- added support for building against Ipopt >= 3.13
2033- unify compiler switches for Intel compiler and avoid problem with doubly defined object together with CPLEX
2034
2035Fixed bugs
2036----------
2037
2038- fix and improve memory handling in symmetry computation
2039- fix shown number of applied conflicts in solving statistics
2040- fix wrongly skipping strong branching call and using old information if LP was solved with 0 iterations
2041- fix minor bug in cut score calculation
2042- fixed several bugs related to rounding locks of variables not being updated correctly
2043- small fix in cons_varbound.c to skip changing bounds of multi-aggregated variables in separation callback
2044- fixed issue in SCIPtightenVar* and SCIPinferVar* that occurs for small bound changes
2045- fixed rejecting minimal boundchange that changed sign of variable, even though SCIPisLb/UbBetter approved it
2046- fixed issue in generateCutNonConvex() which is triggered when adding quadratic constraints during the solving process
2047- fixed bug in freeing the reoptimization data if no problem exists
2048- fixed bug in SCIPreoptReleaseData() when freeing all stored constraints
2049- fixed bug when freeing the transformed problem via interactive shell if reoptimization is enabled
2050- fixed two issues related to (near-)redundant logicor constraints in presolving
2051- fixed counting of aggregations in XOR constraint handler
2052- fixed handling of unbounded solutions
2053- fixed update of LP size information when an LP error occured during probing
2054- handle special case of variable bound constraints during aggregating variables
2055- tighten sides of linear constraints before trying to upgrade them to more specialized constraints (knapsack, logic-or etc.) when calling SCIPupgradeConsLinear()
2056- fixed an issue in repair heuristic in the case of loose (noncolumn) variables
2057- allow user to correctly set heuristics/alns/(un)fixtol
2058- fixed an issue in heur_completesol which is triggered during bound widening of unbounded continuous variables
2059- fixed bug in cons_indicator if addopposite is true
2060- fixed bug in sepa_disjunctive: treat case that conflictgraph is empty
2061- added safety check in conversion to rational number to avoid overflow
2062- fixed bug in interval evaluation with power-operator in certain situations
2063- fixed behavior of SCIPmatrixCreate() regarding memory management and column generation
2064- SCIPmatrixCreate() returns complete=FALSE when locks do not add up
2065- fixed bug in sepa_oddcylce when variables are fixed
2066- fixed numerical issues related to tighter constraint sides in varbound constraint handler
2067- fixed update of watchedvars in logicor constraint handler in case of a restart during the tree
2068- fixed treatment of multi-aggregated variables in logicor constraint handler
2069- handle special case of redundant implications
2070- fixed numerical issue related to almost-0-values in pseudosolution conflict analysis
2071- fixed numerical issue related to very large greatest common dividers in linear constraint handler
2072- avoid using implications on multiaggregated variables when propagating implications
2073- fixed creation of (Lagrangian) variable bounds in the OBBT propagator
2074- fixed sorting of primal solutions
2075- fixed cleaning of clean buffer in conflict analysis
2076- avoid probing on variables with huge bounds in shift and propagate heuristic
2077- fix issue in printing solutions for variables that have been added by the dual sparsify presolver
2078- fix issue related to fixing redundant logic-or constraints after presolving
2079- fixed bug when parsing logic-or and and-constraints
2080- fixed wrong assert in updateLazyBounds()
2081- fixed bug in pricestore, which resulted in too many problem variables being added
2082- fixed bug in cons_knapsack where weight of clique was not reset after an infeasibility was detected
2083- fixed bug in presol_inttobinary which did not take into account that the aggregation could be rejected due to numerics
2084- fixed bug in debug solution mechanism in connection to variables created by presol_inttobinary
2085- fixed wrong indexing while undoing the implications from a redundant variable in SCIPshrinkDisjunctiveVarSet
2086- redundancy checks in SCIPnodeAddBoundinfer now take a possible change to an active variable into account
2087- fixed adding already added quadratic rows to NLP relaxation during solve
2088- fixed issue related to variable locks in the varbound constraint handler
2089- fixed bug in the quadratic constraint handler when changing infinite constraint sides
2090- fixed sorting of variables in linear constraint handler
2091- added additional checks to ensure numerical stability of dual proofs
2092- fixed a case when activities of a linear constraint got unreliable but where still used for reductions
2093- ensure that lhs <= rhs for linear constraints (without tolerances)
2094- make handling of read errors in SCIPfread() consistent between version with and without ZLIB
2095- correctly drop variable events in cons_indicator in restart
2096- fixed bug in cons_orbitope with upgrading of orbitope constraints
2097- additional checks in some presolvers for time limit being exceeded
2098- fixed bug in presolving of cons_varbound with multi-aggregated variables
2099- improve numerics in conflict analysis by using double-double arithmetic
2100- fixed bound acceptance condition to avoid inconsistencies
2101- fixed numerics in pseudoobj propagator by using double-double arithmetic
2102
2103Miscellaneous
2104-------------
2105
2106- modified display column for memory usage ("mem"), which reports the memory usage most of the time, but shows the creator name
2107 (heuristic, relaxation handler, LP relaxation, strong branching, pseudo solution) of every new incumbent solution. Together with this change,
2108 heuristic display characters have been unified to represent the type of the heuristic
2109 (diving, Large neighborhood search, propagation, etc.), see also type_heur.h.
2110- added assert that ensures that the locks of a variable have been decreased to 0 when it is freed
2111- added more output for completing a partial solution
2112- checks in debug mode that clean buffer memory is really clean when being freed are now disabled by default
2113- don't compute symmetries if reoptimization is enabled
2114- prefer integral values when fixing an almost-fixed continuous variable in the trivial presolver
2115- changed the name of the variable that is added by the OSiL reader to represent the quadratic or nonlinear parts of the objective function
2116- SCIP_EXPORT is now defined as __attribute__((__visibility__("default"))) if GCC and no SCIP config header is used
2117
2118@page RN60 Release notes for SCIP 6.0
2119
2120@section RN602 SCIP 6.0.2
2121*************************
2122
2123Features
2124--------
2125
2126- The abspower constraint handler now passes more accurate convexity
2127 information to the NLP relaxation.
2128
2129Examples and applications
2130-------------------------
2131
2132- added parsing functionality for optcumulative constraints in CIP format
2133
2134Interface changes
2135-----------------
2136
2137### Interfaces to external software
2138
2139- Updated the Mosek LP solver interface to support Mosek 9.0.
2140
2141Build system
2142------------
2143
2144### Cmake
2145
2146- new target to 'doc' to build documentation
2147- ctests now fail if parameter file not found
2148- add flag STATIC_GMP and improve GMP find module
2149- remove non-API methods from library (API methods use new macro SCIP_EXPORT)
2150- increase minimal required CMake version to 3.3
2151- correct paths and dependency information when installing SCIP
2152
2153Fixed bugs
2154----------
2155- fixed SCIP-Jack presolving bug that could lead to wrong results for Steiner arborescence problems
2156- fixed wrong unboundedness result in case not all constraints were already in the LP and enforcement was
2157 skipped because an optimal solution was found
2158- fixed wrong enforcement of constraints in the disjunction constraint handler
2159- fixed wrong behavior of concurrent solve ignoring initial solutions
2160- fixed bug in concurrent solve when problem was already solved in presolving
2161- aggregate non-artificial integer variable for XOR constraints with two binary variables and delete constraint
2162- copy the objective offset when copying the original problem
2163- fixed bug in SCIPlpiGetBInvARow in lpi_cpx using wrong size of resulting vector
2164- fixed quadratic runtime behavior in sepa_aggregation
2165- fixed statistics of separators
2166- improve numerical stability in varbound constraint handler by using double-double arithmetic
2167- fixed bug in propagation of dual proofs
2168- fixed bugs that arise for multiaggregated indicator variables by disallowing multiaggregation for them
2169- improve numerical stability in SCIPcomputeBilinEnvelope* by using double-double arithmetic
2170- fixed bug related to releasing pending bound changes in tree.c
2171- set STD FENV_ACCESS pragma to on in code that changes floating-point rounding mode
2172- disable GCC optimizations in main interval arithmetic code to prevent wrong optimizations
2173- fixed wrong assert in cons_xor concerning the variable type
2174- fixed different behavior of SCIPisLbBetter and SCIPisUbBetter between having NDEBUG defined or not
2175- correctly handle bound disjunctions in symmetry detection
2176- fixed issue in reliability branching related to the LP error flag not being reset
2177- fixed treatment of near-infinite bounds in shiftandpropagate's problem transformation
2178- fixed handling of infinite values in SCIPcomputeHyperplaneThreePoints()
2179- fixed comparisons of infinite values in heur_intshifting.c and heur_shifting.c
2180- fixed bug related to updating unprocessed cuts in the cutpool
2181- fixed bug related to enabling quadratic constraints during `CONSINITLP`
2182- add missing SCIP_EXPORT for functions used by GCG
2183- fixed memory leak and wrong initialization for trival cases in cons_symresack.c
2184- fixed bug with upgrading to packing/partitioning orbitopes
2185- fixed bug with the status while upgrading in presol_symbreak.c
2186- fixed wrong stage while clearing the conflict store
2187- fixed behavior of SCIPfixVar() by setting infeasible pointer to TRUE if fixval lies outside variable domain
2188- allow tightenVar() in SCIP_STAGE_PROBLEM stage
2189- fixed bug in cumulative constraint handler when separating the LP solution
2190- fixed issues with integer overflow in cumulative constraint handler
2191- fixed bug where the convexity of Benders' decomposition subproblems was checked even when users defined subproblem
2192 solving methods. Now, as per the documentation, the user must explicitly state whether the subproblem is convex
2193- fixed wrong indexing in heur_dualval
2194- fixed issue with basis status in SoPlex LPi
2195
2196Miscellaneous
2197-------------
2198
2199- statistics now output primal/dual bounds if objective limit is reached
2200- memory check in debug mode is now disabled by default
2201- message is now provided to the user to inform that automatic Benders' auxiliary variable lower bound computations are
2202 not activated when user defined subproblem solving methods are present
2203- corrected documentation of the primalgap in SCIP; describe when it will be infinite
2204
2205@section RN601 SCIP 6.0.1
2206*************************
2207
2208Features
2209--------
2210
2211- when using a debug solution every (multi-)aggregation will be checked w.r.t. this solution
2212
2213Performance improvements
2214------------------------
2215
2216- try greedy solution first before solving knapsack exactly using dynamic programming in SCIPsolveKnapsackExactly,
2217 compute greedy solution by weighted median selection.
2218- don't consider implied redcost by default in the reduced cost propagator
2219
2220Interface changes
2221-----------------
2222
2223### Deleted and changed API methods and macros
2224
2225- The preprocessor macro NO_CONFIG_HEADER now needs to be defined when
2226 including SCIP header files from a SCIP build or installation that
2227 has been build via the Makefile-only build system.
2228
2229- The following preprocessor macros have been renamed:
2230 WITH_ZLIB to SCIP_WITH_ZLIB, WITH_GMP to SCIP_WITH_GMP, WITH_READLINE
2231 to SCIP_WITH_READLINE, NO_SIGACTION to SCIP_NO_SIGACTION, NO_STRTOK_R
2232 to SCIP_NO_STRTOK_R, ROUNDING_FE to SCIP_ROUNDING_FE, ROUNDING_FP to
2233 SCIP_ROUNDING_FP, ROUNDING_MS to SCIP_ROUNDING_MS. Note, however, that
2234 the names of macros NO_RAND_R and NO_STRERROR_R have not been changed
2235 so far.
2236
2237### New API functions
2238
2239- SCIPhashmapInsertInt(), SCIPhashmapSetImageInt(), and SCIPhashmapGetImageInt() to use integer values as images in hashmaps
2240
2241### Command line interface
2242
2243- warn about coefficients in MPS files with absolute value larger than SCIP's value for infinity
2244
2245### Changed parameters
2246
2247- default clock type for timing is now wallclock
2248
2249Unit tests
2250----------
2251
2252- added unit tests for exact knapsack solving and (weighted) median selection algorithms
2253
2254Build system
2255------------
2256
2257### Cmake
2258
2259- add missing GMP dependency when compiling with SYM=bliss
2260- add DL library when linking to CPLEX to avoid linker errors
2261- new config.h header defining the current build configuration, e.g. SCIP_WITH_GMP
2262
2263Fixed bugs
2264----------
2265
2266- fixed handling of weights in cons_sos1 and cons_sos2 (NULL pointer to weights)
2267- fixed handling of unbounded LPs in SCIP and in several LPIs; added heuristic method to guess solution
2268- the STO reader is capable of handling scenarios defined using lower case "rhs"
2269- fixed OPB reader for instances without explicit plus signs
2270- correct dual solution values for bound constraints
2271- fixed recognition of variable with only one lock in cons_bivariate, cons_quadratic, and cons_nonlinear
2272- fixed update of constraint violations in solution repair in cons_bivariate, cons_quadratic, and cons_nonlinear
2273- print error message and terminate if matrix entries of a column are not consecutive in mps format
2274- fixed incorrect handling of fixed variables when transfer of cuts from LNS heuristic for Benders' decomposition
2275- fix returning local infeasible status by Ipopt interface if Ipopt finds problem locally infeasible
2276- skip attempt to apply fixings in linear constraint handler during solving stage as LP rows cannot change anymore
2277- fixed bug when reading >= indicator constraints in MPS format
2278- fix issue with nodes without domain changes if we ran into solution limit in prop_orbitalfixing
2279- fixed unresolved reference to CppAD's microsoft_timer() function on builds with MS/Intel compilers on Windows
2280- ignore implications added through SCIPaddVarImplication() that are redundant to global bounds also in the
2281 special case of an implication between two binary variables; also, use implications instead of cliques in the case
2282 of a binary implied variable with nonbinary active representative
2283- fixed bug with aggregated variables that are aggregated in propagation of cons_sos1
2284- fixed some special cases in SCIPselect/SCIPselectWeighted methods
2285- relaxed too strict assertion in Zirounding heuristic
2286- fixed the upgrade routine to XOR constraints: aggregate integer variable if its coefficient has the wrong sign
2287- fixed handling of nonartificial parity variables when deleting redundant XOR constraints
2288- earlier deletion of trivial XOR constraints (at most 1 operator left)
2289- fixed wrong hashmap accesses and added sanity check for the correct hashmap type
2290- avoid copying of unbounded solutions from sub-SCIPs as those cannot be checked completely
2291- corrected the output of the first LP value in case of branch-and-price
2292- fixed possible integer overflow, which led to wrong conclusion of infeasibility, in energetic reasoning of cons_cumulative.c
2293
2294Miscellaneous
2295-------------
2296- do not scale linear constraints to integral coefficients
2297
2298@section RN600 SCIP 6.0.0
2299*************************
2300
2301Features
2302--------
2303
2304- new diving heuristic farkasdiving that dives into the direction of the pseudosolution and tries to construct Farkas-proofs
2305- new diving heuristic conflictdiving that considers locks from conflict constraints
2306- restructuring of timing of symmetry computation that allows to add symmetry handling components within presolving
2307- `lp/checkstability` is properly implemented for SoPlex LPI (spx2)
2308- new branching rule lookahead that evaluates potential child and grandchild nodes to determine a branching decision
2309- limits on the number of presolving rounds a presolver (maxrounds) or propagator/constraint handler (maxprerounds)
2310 participates in are now compared to the number of calls of the particular presolving method, not the number of
2311 presolving rounds in general, anymore
2312- new miscellaneous methods for constraints that have a one-row linear representation in pub_misc_linear.h
2313- a Benders' decomposition framework has been added. This framework provides the functionality for a user to solve a
2314 decomposed problem using Benders' decomposition. The framework includes classical optimality and feasibility cuts,
2315 integer optimality cuts and no-good cuts.
2316- add statistic that presents the number of resolves for instable LPs
2317- new readers for stochastic programming problems in SMPS format (reader_sto.h, reader_smps.h)
2318
2319Performance improvements
2320------------------------
2321
2322- cuts generated from certain quadratic constraints with convex feasible region are now global
2323- performance improvements for Adaptive Large Neighborhood Search heur_alns.c
2324 + all neighborhoods now start conservatively from maximum fixing rate
2325 + new default parameter settings for bandit selection parameters
2326 + no adjustment of minimum improvement by default
2327- improved bound tightening for some quadratic equations
2328- constraint handler checking order for original solutions has been modified to check those with negative check priority
2329 that don't need constraints after all other constraint handlers and constraints have been checked
2330- deactivate gauge cuts
2331
2332Examples and applications
2333-------------------------
2334
2335- new example `brachistochrone` in CallableLibrary examples collection; this example implements a discretized model to
2336 obtain the trajectory associated with the shortest time to go from point A to B for a particle under gravity only
2337- new example `circlepacking` in CallableLibrary examples collection; this example models two problems about packing
2338 circles of given radii into a rectangle
2339- new price-and-branch application for the ringpacking problem
2340- new stochastic capacitated facility location example demonstrating the use of the Benders' decomposition framework
2341
2342Interface changes
2343-----------------
2344
2345### New and changed callbacks
2346
2347- added parameter locktype to `SCIP_DECL_CONSLOCK` callback to indicate the type of variable locks
2348
2349### Deleted and changed API methods
2350
2351- Symmetry:
2352 + removed function SCIPgetTimingSymmetry() in presol_symmetry.h since this presolver does not compute symmetries independent
2353 of other components anymore
2354 + additional argument `recompute` to SCIPgetGeneratorsSymmetry() to allow recomputation of symmetries
2355
2356- Random generators:
2357 + the seed of SCIPinitializeRandomSeed() is now an unsigned int
2358 + the seed of SCIPsetInitializeRandomSeed() is now an unsigned int and it returns an unsigned int
2359 + new parameter for SCIPcreateRandom() to specify whether the global random seed shift should be used in the creation of
2360 the random number generator
2361
2362- Miscellaneous:
2363 + additional arguments `preferrecent`, `decayfactor` and `avglim` to SCIPcreateBanditEpsgreedy() to choose between
2364 weights that are simple averages or higher weights for more recent observations (the previous default).
2365 The last two parameters are used for a finer control of the exponential decay.
2366 + functions SCIPintervalSolveUnivariateQuadExpression(), SCIPintervalSolveUnivariateQuadExpressionPositive(), and
2367 SCIPintervalSolveUnivariateQuadExpressionPositiveAllScalar() now take an additional argument to specify already
2368 existing bounds on x, providing an entire interval ([-infinity,infinity]) gives previous behavior
2369
2370### New API functions
2371
2372- SCIPintervalSolveUnivariateQuadExpressionNegative()
2373- SCIPvarGetNLocksDownType() and SCIPvarGetNLocksUpType()
2374- SCIPaddConsLocksType()
2375- SCIPconsIsLockedTypePos(), SCIPconsIsLockedTypeNeg(), SCIPconsIsLockedType(), SCIPconsGetNLocksTypePos() and SCIPconsGetNLocksTypeNeg()
2376- SCIPstrncpy(), a safe version of strncpy()
2377
2378### Changed parameters
2379
2380- Removed parameters:
2381 - `heuristics/alns/stallnodefactor` as the stall nodes are now controlled directly by the target node limit within the heuristic
2382 - `presolving/symmetry/computepresolved` since this presolver does not compute symmetries independent of other components anymore
2383 - `separating/maxincrounds`
2384
2385### New parameters
2386
2387- `lp/checkfarkas` that enables the check of infeasibility proofs from the LP
2388- `heuristics/alns/unfixtol` to specify tolerance to exceed the target fixing rate before unfixing variables, (default: 0.1)
2389- `propagating/orbitalfixing/symcomptiming` to change the timining of symmetry computation for orbital fixing
2390- `lp/alwaysgetduals` ensure that the dual solutions are always computed from the recent LP solve
2391- `display/relevantstats` indicates whether the small relevant statistics are displayed at the end of solving
2392- `propagating/orbitalfixing/performpresolving` that enables orbital fixing in presolving
2393- `presolving/symbreak/addconsstiming` to change the timining of symmetry computation for symmetry handling inequalities
2394- `propagating/orbitalfixing/enabledafterrestarts` to control whether orbital fixing is enabled after restarts
2395- `benders/∗` new submenu for Benders' decomposition related settings. This includes the settings related to the
2396 included Benders' decompositions and the general Benders' decomposition settings.
2397- `benders/<decompname>/benderscuts/∗` submenu within each included Benders' decomposition to control the Benders'
2398 decomposition cuts. The cuts are added to each decomposition separately, so the setting are unique to each
2399 decomposition.
2400
2401### Data structures
2402
2403- new enum `SCIP_LOCKTYPE` to distinguish between variable locks implied by model (check) constraints (`SCIP_LOCKYPE_MODEL`)
2404 and variable locks implied by conflict constraints (`SCIP_LOCKYPE_CONFLICT`)
2405- expression interpreter objects are now stored in the block memory
2406
2407Deleted files
2408-------------
2409
2410- removed presolving plugin presol_implfree
2411- separated scip.c into several smaller implementation files scip_*.c for better code overview; scip.c was removed,
2412 but the central user header scip.h remains, which contains includes of the separated headers
2413
2414Fixed bugs
2415----------
2416
2417- fixed bug in gcd reductions of cons_linear regarding an outdated flag for variable types
2418- fixed bug in heur_dualval regarding fixing routine for integer variables
2419- suppress debug solution warnings during problem creation stage
2420- fixed check for activated debugging solution in components constraint handler
2421- fixed potential bug concerning solution linking to LP in SCIPperformGenericDivingAlgorithm()
2422- fixed reward computation in ALNS on continuous, especially nonlinear, problems
2423- fixed bug in freeing reoptimization data if problem was solved during presolving
2424- fixed check of timing in heur_completesol
2425- fixed wrong propagation in optcumulative constraint handler
2426- fixed non-deterministic behavior in OBBT propagator
2427- don't disable LP presolving when using Xpress as LP solver
2428- fixed possible `NULL` pointer usage in cons_pseudoboolean
2429- ensured that SCIPgetDualbound() returns global dual bound instead of the dual bound of the remaining search tree
2430- fixed rare division-by-zero when solving bivariate quadratic interval equation
2431- use total memory for triggering memory saving mode
2432- fix parsing of version number in the CMake module for Ipopt
2433- fixed handling of implicit integer variables when attempting to solve sub-MIP in nlpdiving heuristic
2434- added workaround for bug when solving certain bivariate quadratic interval equations with unbounded second variable
2435- fixed bug with releasing slack variable and linear constraint in cons_indicator
2436- fixed problem when writing MPS file with indicator constraints with corresponding empty linear constraints
2437- fixed bug in heur_vbound triggered when new variables were added while constructing the LP
2438- fixed bug with unlinked columns in SCIProwGetLPSolCutoffDistance()
2439
2440Miscellaneous
2441-------------
2442
2443- updated CppAD to version 20180000.0
2444- remove LEGACY mode, compiler needs to be C++11-compliant
2445
2446@page RN50 Release notes for SCIP 5.0
2447
2448@section RN501 SCIP 5.0.1
2449*************************
2450
2451Features
2452--------
2453
2454- SCIP executable handles the `SIGTERM` signal. If the process receives a `SIGTERM`, SCIP terminates the solution process with a
2455 new `SCIP_STATUS` code `SCIP_STATUS_TERMINATE` and displays all relevant statistics before exiting.
2456- add number of conflict constraints found by diving heuristics to statistics
2457- allow output of lower bounds for visualization
2458- added symmetry detection for linking constraints
2459
2460Performance improvements
2461------------------------
2462
2463- disable disaggregation of quadratic constraints by changing the default for `constraints/quadratic/maxdisaggrsize` to 1
2464 (disaggregation can still be very helpful on some instances, but also seems hurtful on others)
2465
2466- Cuts:
2467 - increased threshold when to scale up cuts that are generated by nonlinear constraint handlers
2468 - test additional scaling factors in CMIR cut generation heuristic
2469 - cleaned up implementation of the cut selection procedure and added new cut quality measure
2470 - use random tie-breaking in cut selection
2471
2472Interface changes
2473-----------------
2474
2475### New API functions
2476
2477- new methods SCIPtryTerminate() and SCIPterminated() in scip/interrupt.h for handling of SIGTERM signals.
2478- new method SCIPselectCuts() to run SCIP's cut selection procedure on a given array of cuts
2479
2480### Changed parameters
2481
2482- rename parameter `constraints/orbisack/orbisack/coverseparation` to `constraints/orbisack/coverseparation`
2483
2484### New parameters
2485
2486- `visual/displb` that enables output of lower bounds for visualization
2487- `presolving/symmetry/displaynorbitvars` (whether we display the number of affected variables in the statistics)
2488- `separating/efficacyfac` to change the weight of the efficacy in cut score calculation
2489- `separating/dircutoffdistfac` to change the weight of the directed cutoff distance in cut score calculation
2490
2491### Data structures
2492
2493- new `SCIP_STATUS` code `SCIP_STATUS_TERMINATE` in scip/interrupt.h for handling of SIGTERM signals.
2494
2495Unit tests
2496----------
2497
2498- expanded unit tests of the lpis
2499- added check to unit tests that problem is not solved after every change
2500
2501Fixed bugs
2502----------
2503
2504- fixed LP status to unsolved when marking LP to be resolved if objective limit has changed
2505- copy parameter settings to sub-SCIPs in SCIPcopyLargeNeighborhoodSearch() also when copying only LP rows
2506- fixed a check for fixed variables in Binpacking example
2507- generate deprecation warnings when using SCIPaddCut
2508- fix bug in sepa_gomory if cut is a bound change
2509- fixed handling of infinite bounds in cons_sos1
2510
2511- Constraints:
2512 - fixed bug while scaling linear constraints
2513 - don't delete conflict constraints that were transformed into model constraints during a restart
2514 - fixed treatment of variable aggregations in knapsack constraint handler that led to wrong propagations
2515
2516- LP Interface:
2517 - fixed LPI status after changing objective in lpi_cpx, lpi_grb, lpi_xprs, lpi_msk
2518 - fixed and unified asserts in LPIs
2519 - retrieve interior solution instead of (possibly non-existing) basic solution from mosek after using barrier without crossover in lpi_msk
2520 - fixed bug with `NULL` pointer handling in LPIs
2521
2522- Heuristics:
2523 - fixed wrong cast in LP iteration limit computation in proximity search heuristic
2524 - fixed check for time limit in heur_nlpdiving
2525 - improved numerics and fixed stop criterion in zirounding heuristic
2526
2527@section RN500 SCIP 5.0.0
2528*************************
2529
2530Features
2531--------
2532
2533- new numerical solution violations get printed when checksol is called
2534- added analysis of the clique table which identifies possible aggregations via the search for
2535 strongly connected components and may detect infeasible assignments on the way
2536- added macros to do computations with a higher precision by using double-double arithmetic
2537- extended conflict analysis by analyzing dual solutions of boundexceeding LPs
2538- revised internal debugging mechanism to check against a user given debug solution (debug.h)
2539
2540- Heuristic:
2541 - add new heuristic MPEC that solves a MPEC reformulation of a mixed-binary nonlinear problem by regularized NLP reformulations
2542 - new primal heuristic ALNS that orchestrates eight different LNS heuristics adaptively
2543 using algorithms for the multi-armed bandit problem
2544 - three bandit selection algorithms to face sequential decision problems under uncertainty
2545
2546- Presolving and symmetry:
2547 - added presol_symmetry.c for computing and storing symmetry information of a MIP
2548 - added presol_symbreak.c to detect special symmetry structures and to add symmetry handling constraints
2549 - SCIP can now automatically detect and compute symmetries in MIPs (if a graph automorphism code is linked in)
2550 - added cons_symresack.c to handle permutation symmetries in a binary programs via inequalities and propagation
2551 - added cons_orbisack.c to handle special permutation symmetries in a binary programs via inequalities and propagation
2552 - cons_orbitope.c can now handle full orbitopes as well
2553
2554- Propagator:
2555 - added new propagator orbital fixing
2556 - utilizing linear inequalities to compute stronger linearizations for bilinear terms; the inequalities are computed in
2557 the OBBT propagator
2558
2559- Cuts:
2560 - added API for aggregating rows for generating cuts which uses double-double arithmetic internally
2561 - added filtering of parallel cuts in the cut pool
2562
2563- Plugins:
2564 + added new plugin type `table` for adding user-defined statistics tables
2565 + new presolving plugin presol_sparsify that tries to cancel nonzero coefficients in linear constraints by adding
2566 multiples of linear equalities
2567
2568Performance improvements
2569------------------------
2570
2571- use disjoint set to reduce peak memory usage and time to compute of clique table connectedness information
2572- add and use RESTRICT macro for some pointers
2573- improved the implementation of SCIPvarGetActiveRepresentatives
2574- speed-up reverse propagation
2575- removed bestrelaxsol and directly access relaxation solution instead to decrease overhead when using relaxation handlers
2576- for fast presolving emphasis, disable use of implications in logicor presolving
2577- use limit on the total number of nonzeros added to the clique table during the greedyCliqueAlgorithm of cons_knapsack.c
2578- revised disaggregation of quadratic constraints: the number of created constraints can now be controlled and the
2579 disaggregated constraints are scaled in order to increase numerical accuracy
2580- disabled reformulation of products of a binary variable with a linear term that does not solely involve binary variables
2581- speed up creation of LP in the computation of relative interior points
2582- improved dual ray analysis
2583- drop events of disabled linear constraints to reduce event processing effort
2584
2585- Separation:
2586 - new implementation of zerohalf separator
2587 - enabled cutting plane separation in the tree
2588 - improved cut selection and management
2589 - improved cut post-processing: apply coefficient tightening, enforce maximal dynamism
2590
2591- Heuristics:
2592 - improved selection of rows in CMIR aggregation heuristic
2593 - generate lifted flowcover cuts in CMIR cut generation heuristic
2594 - faster implementation of CMIR cut generation heuristic
2595 - use LP solution polishing during probing and diving mode to activate it during many primal heuristics; remains disabled
2596 during strong branching and OBBT
2597 - improved versions of the clique and variable bound pre-root heuristics that are often able to fix many more variables
2598
2599Interface changes
2600-----------------
2601
2602### New and changed callbacks
2603
2604- New types:
2605 - added new abstract selection algorithm `SCIP_BANDIT` together with callbacks
2606 - added new types for symmetry handling
2607
2608- NLP interface:
2609 - dropped NLP termination status `SCIP_NLPTERMSTAT_UOBJLIM`
2610
2611- NLP callbacks:
2612 - added parameter `objval` to `SCIP_DECL_NLPIGETSOLUTION` for returning the optimal objective value (can be set to `NULL`)
2613
2614- Separation callbacks:
2615 - added parameter `allowlocal` to `SCIP_DECL_SEPAEXECLP` and `SCIP_DECL_SEPAEXECSOL` to switch generation of locally valid cuts
2616 - added parameter `dstatssize` to `SCIP_DECL_NLPIDELVARSET` and `SCIP_DECL_NLPIDELCONSSET`
2617
2618### Deleted and changed API methods
2619
2620- Branching rules:
2621 - removed parameter `allowaddcons` from SCIPselectVarPseudoStrongBranching(), SCIPselectVarStrongBranching(), and
2622 SCIPincludeBranchruleRelpscost()
2623
2624- Constraint Handlers:
2625 - generalized SCIPcreateConsOrbitope() and SCIPcreateConsBasicOrbitope() method to three orbitope types (full, partitioning, packing)
2626
2627- Cutting plane separation methods:
2628 - changed function signature of SCIPcalcMIR()
2629 - changed function signature of SCIPcalcStrongCG()
2630 - new method SCIPaddRow() to replace deprecated SCIPaddCut()
2631 - removed parameter `scaling` from SCIPgetRowprepViolation()
2632 - added parameter `allowlocal` to SCIPseparateSol()
2633
2634- LP interface:
2635 - replaced LP parameters `SCIP_LPPARAM_LOBJLIM` and `SCIP_LPPARAM_UOBJLIM` by `SCIP_LPPARAM_OBJLIM`
2636
2637- NLP interface:
2638 - SCIPnlpStatisticsCreate() and SCIPnlpStatisticsFree() now require a pointer to blockmemory as parameter
2639 - added parameter `objval` to SCIPnlpiGetSolution() of NLPIs for returning the optimal objective value (can be set to `NULL`)
2640 - added parameter `varnameslength` to SCIPexprParse()
2641 - added parameter `dstatssize` to SCIPnlpiDelVarSet() and SCIPnlpiDelConsSet()
2642 - added modifier const to `exprtree` parameter of SCIPnlpiChgExprtree()
2643
2644- Primal heuristics:
2645 - SCIPheurPassIndicator() has a new parameter which allows to pass the objective of the solution
2646
2647- Relaxator methods:
2648 - added parameter `includeslp` to SCIPmarkRelaxSolValid(), SCIPsetRelaxSolVals() and SCIPsetRelaxSolValsSol();
2649 - removed parameter `includeslp` from SCIPrelaxCreate() and SCIPincludeRelax()
2650 - removed functions SCIPrelaxIncludesLp() and SCIPrelaxSetIncludesLp()
2651 - replaced method SCIPgetRelaxFeastolFactor() by SCIPrelaxfeastol() and added SCIPchgRelaxfeastol()
2652
2653- Misc:
2654 - changed return type of SCIPcliqueGetId() from `int` to `unsigned int`
2655 - SCIPsolveParallel() is deprecated; use SCIPsolveConcurrent() instead
2656 - removed SCIPvarGetCliqueComponentIdx(); the connectedness information of the clique table is now stored as a
2657 `SCIP_DISJOINTSET` member of the clique table and cannot be publicly accessed
2658 - added parameter `copytables` to SCIPcopyPlugins()
2659 - SCIPsolveParallel() has been deprecated, use the new method SCIPsolveConcurrent() instead
2660 - allowed SCIPgetNConss() in stage `SCIP_STAGE_INITSOLVE`
2661
2662### New API functions
2663
2664- SCIPaddRow() to replace deprecated SCIPaddCut()
2665- methods to display linear constraint classification types; use SCIPclassifyConstraintTypesLinear()
2666 after reading a problem to classify linear constraint types
2667- public methods SCIPvariableGraphBreadthFirst() and SCIPvariableGraph{Create,Free}() to
2668 perform breadth-first search on the variable constraint graph used by the GINS and ALNS heuristics
2669- SCIPsetProbingLPState() to install given LP state and/or norms at the current probing node
2670- SCIPbranchcandGetLPMaxPrio() and SCIPbranchcandGetExternMaxPrio() to query the maximal branching priority of given
2671 branching candidates; also added SCIPbranchcandGetNPrioLPCands() to access the number of LP candidates with this priority.
2672- SCIPupdateSolIntegralityViolation(), SCIPupdateSolBoundViolation(), SCIPupdateSolLPRowViolation(),
2673 SCIPupdateSolConsViolation() and SCIPupdateSolLPConsViolation() for updating numerical solution violations, as well as
2674 SCIPactivateSolViolationUpdates() and SCIPdeactivateSolViolationUpdates() for activating/deactivating violation updates globally
2675- SCIPsetSubscipDepth() to set the depth of SCIP as a copied subproblem during problem stage
2676- SCIPdivesetGetNSols() to query the number of found solutions from a diveset.
2677- SCIPnextafter() that wraps different nextafter methods to return the next representable value after a given value
2678- SCIPlinConsStats{Create,Free,GetTypeCount,GetSum}() and SCIPprintLinConsStats() to work with linear constraint classification through the C API
2679- SCIPgetRowNumIntCols() that returns the number of integer columns in a row
2680- SCIPsetSlackVarUb() to control upper bound of slack variable in cons_indicator
2681
2682- Data structures:
2683 - methods SCIPrandomCreate() and SCIPrandomFree() are no longer public and should be replaced by SCIPcreateRandom() and
2684 SCIPfreeRandom(), respectively (the new methods respect the global parameter `randomization/randomseedshift` automatically)
2685 - methods SCIPdigraphCreate() and SCIPdigraphCopy() are no longer public and should be replaced by SCIPcreateDigraph() and
2686 SCIPcopyDigraph(), respectively, which receive a SCIP argument and are more robust towards future interface changes
2687
2688- Bilinear:
2689 - SCIPgetAllBilinearTermsQuadratic() to access data of all existing bilinear terms in quadratic constraints
2690 - SCIPaddBilinearIneqQuadratic() to propose an inequality with two variables that appear in a bilinear term
2691 - SCIPcomputeBilinEnvelope{1,2}() to compute a linearization of a bilinear term when considering at most two linear inequalities
2692
2693- Clique:
2694 - SCIPcliqueGetIndex() which returns the unique identifier for the given clique
2695 - SCIPgetNCliquesCreated() which returns the number of cliques created so far
2696
2697- Cutting plane separation methods:
2698 - SCIPisCutNew() that returns whether a cut is already present in the global cut pool
2699 - SCIPgetSepaMinEfficacy() to access separating/minefficacy(root)
2700
2701- Interfaces:
2702 - interface methods to create and use bandit algorithms implemented as SCIP core plugins
2703 - interface methods for aggregating rows and computating MIP cuts, see cuts.h
2704 - interface method SCIPsetRandomSeed() to (re)set a random number generator seed
2705
2706### Command line interface
2707
2708- new interactive shell functionality to display linear constraint classification types;
2709 use `display linclass` after reading a problem to classify linear constraint types
2710- new command line parameter `-r` to pass a nonnegative integer as random seed.
2711
2712### Interfaces to external software
2713
2714- added interface to the NLP solver WORHP
2715- added interface to the NLP solver FilterSQP
2716- added interface to graph automorphism algorithms in `src/symmetry/` (initially only to BLISS)
2717- unify handling of objective limit in LPIs by replacing LPI parameters `SCIP_LPPAR_LOBJLIM` and `SCIP_LPPAR_UOBJLIM` by
2718 `SCIP_LPPAR_OBJLIM`
2719- dropped support for MOSEK < 7.0.0.0
2720
2721### Changed parameters
2722
2723- changed and removed several parameters for zerohalf separator
2724- replaced `constraints/quadratic/disaggregate` by `constraints/quadratic/maxdisaggrsize` to bound
2725 the total number of created constraints when disaggregating a quadratic constraint
2726- new value 3 for parameter `lp/solutionpolishing` to enable LP polishing only during probing and diving mode
2727- parameter `conflict/useboundlp` has new values `d` (only dual solution analysis) and `b` (both, conflict and dual solution analysis)
2728
2729- Heuristics:
2730 - fixed typo `heuristics/completesol/maxunkownrate` has changed to `heuristics/completesol/maxunknownrate`
2731 - replaced parameter `heuristics/{clique,vbounds}/minfixingrate` by `heuristics/{clique,vbounds}/minintfixingrate` and
2732 `heuristics/{clique,vbounds}/minmipfixingrate`, which check the fixing rate before LP solving and after sub-MIP presolve
2733
2734- Separating:
2735 - parameter `separating/maxstallrounds` only applies to nodes in the tree (not the root node, anymore); use the new
2736 parameter `separating/maxstallroundsroot` for the root node
2737 - moved parameters for flowcover and cmir separators to `separating/aggregation`
2738
2739- Removed parameters:
2740 - `constraints/{abspower,bivariate,nonlinear,quadratic,soc}/scaling`
2741 - `constraints/{abspower,bivariate,quadratic,nonlinear}/mincutefficacysepa`
2742 - `constraints/{abspower,bivariate,quadratic,nonlinear}/mincutefficacyenfofac`
2743 - `constraints/soc/minefficacy`
2744 - `conflict/usemir`
2745 - `conflict/prefermir`
2746 - `heuristics/clique/{multiplier,initseed}`
2747 - `separating/feastolfac`
2748 - `separating/orthofac`
2749 - `separating/cgmip/allowlocal` (use parameter passed to separation callback instead)
2750 - `separating/{gomory,strongcg}/maxweightrange`
2751
2752### New parameters
2753
2754- `conflict/prefinfproof` (prefer infeasibility proof to boundexceeding proof)
2755- `conflict/sepaaltproofs`
2756- `constraints/indicator/maxsepanonviolated` to stop separation after separation of non violated cuts
2757- `constraints/orbisack/coverseparation` (whether orbisack cover inequalities should be separated)
2758- `constraints/orbisack/orbiSeparation` (whether facet defining inequalities for orbisack should be separated)
2759- `constraints/orbisack/coeffbound` (maximal value of coefficients in orbisack facet inequalities)
2760- `constraints/orbisack/checkpporbisack` (check whether orbisacks can be strengthened by packing/partitioning constraints)
2761- `constraints/orbisack/checkalwaysfeas` (whether conscheck returns always `SCIP_FEASIBLE`)
2762- `constraints/orbitope/checkpporbitope` (check packing/partitioning orbitopes)
2763- `constraints/orbitope/sepafullorbitope` (separate full orbitopes)
2764- `constraints/orbitope/checkalwaysfeas` (whether conscheck returns always `SCIP_FEASIBLE`)
2765- `constraints/quadratic/{usebilinineqbranch,minscorebilinterms,bilinineqmaxseparounds}`
2766- `constraints/quadratic/disaggrmergemethod` to change the strategy of how to merge independent blocks of quadratic constraints
2767- `constraints/quadratic/mincurvcollectbilinterms` to change the minimal curvature of constraints
2768 to be considered when returning bilinear terms to other plugins
2769- `constraints/quadratic/binreformbinaryonly` to disable reformulation of products of binary and non-binary variables
2770- `constraints/symresack/ppsymresack` (check whether symresacks can be strengthend by packing/partitining constraints)
2771- `constraints/symresack/checkalwaysfeas` (whether conscheck returns always `SCIP_FEASIBLE`)
2772- `expbackoff` to all separators which increases the frequency exponentially over the depth in the tree
2773- `heuristics/completesol/{beforepresol,maxlpiter,maxcontvars}`
2774- `heuristics/{clique,vbounds}/maxbacktracks` to limit the number of backtracks in the fix-and-propagate phase
2775- `heuristics/{clique,vbounds}/uselockfixings` to enable fixing of additional variables based on variable locks
2776- `heuristics/vbounds/{feasvariant,tightenvariant}` to specify the fixing variants used by the vbounds heuristic
2777- `lp/refactorinterval` to change the refactorization interval of the LP solver
2778- `misc/debugsol` to specify a debug solution that should be checked during the solve
2779- `misc/usesymmetry` to determine whether symmetry handling should be used
2780- `presolving/symbreak/conssaddlp` (whether symmetry handling inequalities should be added to the LP)
2781- `presolving/symbreak/addsymresacks` (whether symresacks should be used to handle symmetries)
2782- `presolving/symbreak/computeorbits` (whether symmetry orbits should be computed)
2783- `presolving/symbreak/detectorbitopes` (whether it should be checked if some symmetries can be handled by orbitopes)
2784- `presolving/symmetry/computepresolved` (Whether symmetries are computed after presolving)
2785- `presolving/symmetry/maxgenerators` (maximal number of generators generated by symmetry detection)
2786- `presolving/symmetry/checksymmetries` (whether validity of computed symmetries should be verified)
2787- `propagating/obbt/{itlimitfactorbilin,minnonconvexity,createbilinineqs}`
2788- `propagating/vbounds/minnewcliques` to specify the minimum number of new cliques to trigger another clique table analysis
2789- `propagating/vbounds/{maxcliquesmedium,maxcliquesexhaustive}` to limit the number of cliques relative to the
2790 number of binary variable for performing clique table analysis
2791- `separating/maxincrounds`
2792- `separating/maxlocalbounddist`, `separating/maxcoefratio` and `separating/intsupportfac`
2793- if PaPILO >= 2.1: `presolving/milp/maxbadgesizepar` to limit the maximal badge size if PaPILO is called in parallel mode
2794- if PaPILO >= 2.1: `presolving/milp/maxbadgesizeseq` to limit the maximal badge size if PaPILO is called in sequential mode
2795
2796### Data structures
2797
2798- new type `SCIP_Shortbool` (equal to uint8_t) for storing Boolean values in a more compact manner
2799- new disjoint set data structure `SCIP_DISJOINTSET` to incrementally update connectedness information for a graph on nodes {0,...,n-1}
2800- new red black tree data structure defined in `src/scip/rbtree.{c,h}`
2801- new object `SCIP_LINCONSSTATS`, see type_cons.h, to work with linear constraint classification through the C API
2802- added new type `SCIP_TABLE` together with callbacks to output SCIP statistics
2803
2804Unit tests
2805----------
2806
2807- added several tests for the LP interface
2808- added tests that cover nonempty linear constraint classification types
2809- added tests for the double double arithmetic, the new red black tree data structure, the nlpi, obbt, interval arithmetics,
2810 symmetry computation, objective function changes in probing, computing envelopes of bilinear function, relaxation enforcement
2811
2812Build system
2813------------
2814
2815- added interface to the NLP solver WORHP; set `WORHP=true` in order to link to WORHP
2816- added interface to the NLP solver FilterSQP; set `FILTERSQP=true` in order to link to FilterSQP
2817
2818### Cmake
2819
2820- added support for sanitizers in debug mode and options SANITIZE_ADDRESS, SANITIZE_MEMORY, SANITIZE_UNDEFINED, SANITIZE_THREAD
2821- added option SYM to specify which graph automorphism package (bliss, none) should be used, if available
2822- disable non-standard compliant floating point optimizations in combination with intel compilers
2823- improve Visual Studio compilation
2824- only accept IPOPT version 3.12.0 or higher
2825- preserve correct rpath in library (e.g. path to libipopt) when installing
2826
2827### Makefile
2828
2829- new flag `DEBUGSOL={true,false}` to enable checks against a user given debug solution
2830- added flag SYM to specify which graph automorphism package (bliss, none) should be used
2831- default value for ZIMPL in the Makefile is now `false`
2832
2833Fixed bugs
2834----------
2835
2836- fix wrong statistic display of diving leaf solutions
2837- fixed order of SCIPcalcCliquePartition() in corner case where no cliques are available
2838- fix treatment of infinite lower bound in proximity objective cutoff
2839- fixed minor issue in expression graph simplification
2840
2841- Separator:
2842 - fix linear knapsack relaxation during separation if a binary variable does not have a solution value in [0,1].
2843 - fixed potential ressource leaks in SCIPsolveLinearProb(), expr.c, sepa_eccuts, cons_cumulative.c, cons_nonlinear.c
2844 - fixed bug in cons_orbitope.c, where wrong terminating index in separation of SCIs was used
2845 - fixed wrong mapping of permuted basis indices in gomory separator
2846 - fixed integer objective separator for objective scales < 1
2847
2848- Presolver:
2849 - fixed numerical issues in boundshift presolver when aggregating integer variables
2850 - fixed aggregation of variables in boundshift presolver that contain large variable bounds
2851
2852- Heuristic:
2853 - fixed bug in feasibility pump heuristic when switching on the `usefp20` parameter
2854 - fixed handling of LOOSE variables in locks heuristic
2855 - fixed creation of conflicts in clique heuristic for incomplete LPs
2856
2857- Constraints:
2858 - fixed bug in mps reader. Reader now prints `OBJSENSE` section and tries to generate unique names of constraints
2859 - fixed upgrade to a varbound constraint if abspower constraint contains a multi-aggregated variable
2860 - fixed several bugs related to hashing of constraints/rows in cutpool.c and cons_linear.c
2861 - fixed registration of almost fixed nonlinear variables in abspower constraints
2862
2863- Propagator:
2864 - fixed releasing of variables in the genvbounds propagator in case the problem could be solved during presolving of a restart
2865 - fixed numerical issues in bound widening of variable bound constraint handler and vbound propagator during conflict analysis
2866
2867@page RN40 Release notes for SCIP 4.0
2868
2869@section RN401 SCIP 4.0.1
2870*************************
2871
2872Features
2873--------
2874
2875- added parsing functionality to cardinality constraint handler for CIP format
2876- allow to relax objective limit in reoptimization in presolved stage
2877- suppress excessive printing about numerical troubles in LP on default verblevel (high)
2878
2879Performance improvements
2880------------------------
2881
2882- only accept passed improving solutions in heur_indicator
2883- add and use RESTRICT macro for some pointers
2884- sorting of parents and children for some expression types is now independent of memory layout
2885
2886- Constraints:
2887 - widened a bottleneck in simplifying long signomial sums in a nonlinear constraint
2888 - unified and extended code that improves numerics of cuts generated by nonlinear constraint handlers
2889
2890- Separation:
2891 - stop separation in cons_indicator after maxsepanonviolated many non violated separated cuts
2892 - improve choice of variable to enter support in separation of cons_indicator
2893
2894Interface changes
2895-----------------
2896
2897### New API functions
2898
2899- SCIPvalidateSolve() to compare solving result with an external primal and dual reference value
2900- SCIPisObjChangedProbing() to check whether the objective function has changed during probing mode
2901- SCIPgetDualSolVal() to get the dual solution value of a constraint
2902- SCIPisLPPrimalReliable() and SCIPisLPDualReliable() to check whether the current primal / dual LP solution
2903 were successfully checked for feasibility
2904
2905### Command line interface
2906
2907- New option in the interactive shell to validate the solution against an external primal and dual reference value
2908- added command line option `-o` and command `validatesolve` in interactive shell
2909 to validate the solution against an external primal and dual reference value.
2910
2911### Interfaces to external software
2912
2913- Updated and new interfaces to Mosek 8.1, GAMS and Gurobi
2914- new LP interface to Glop (Google OR tools); CMake only
2915
2916### Changed parameters
2917
2918- renamed parameter `heuristics/completesol/maxunkownrate` to `heuristics/completesol/maxunknownrate`
2919
2920Testing
2921-------
2922
2923- add options to make test target (see Makefile section)
2924
2925Build system
2926------------
2927
2928### Cmake
2929
2930- New CMake build system alongside the usual Makefile setup
2931
2932### Makefile
2933
2934- added make options for specifying EXECUTABLE and OUTPUTDIR variables for the make test target
2935
2936Fixed bugs
2937----------
2938
2939- fixed unintended behavior of interrupt signal handler inside SCIP copies
2940- fixed uninitialized values in SCIP's digraph data structure after calling SCIPdigraphResize()
2941- fixed issue related to SCIPcreateFiniteSolCopy() not being able to remove all infinite fixings
2942- fixed issue in SCIPcopyLimits() w.r.t. soft time limit
2943- fixed bug in dynamic resizing of hashtables and hashmaps
2944- added workaround for bug in primal simplex of cplex 12.7.1.0 occuring when attempting to solve LPs without rows without presolving
2945- fixed bug in binpacking example that might have led to doing the same branching several times
2946- fixed memory issue in binpacking example
2947- in GAMS writer, forbid also various parenthesis characters in gams symbol names
2948- added missing definition of `SCIP_UNUSED` in memory.h if def.h is not included
2949- treat reopt bugs: Avoid numerical problems with changing objective; fix check for changed objective
2950- fixed reading issue in mps reader: integer variables fixed to 0 or 1 are treated as binaries now,
2951 allowing to use them as indicator variables
2952- afternode heuristics are now called even if the node limit was reached and the solving process will be stopped
2953 after the current node
2954- fixed bug when activating probing mode with a non-empty separation storage
2955
2956- LP interfaces:
2957 - fixed guard against using old Gurobi versions in lpi_grb.c: Gurobi 7.5 was not permitted
2958 - fixed wrong handling of unboundedness status in lpi_grb.c
2959 - fixed wrong handling of row basis status in lpi_grb.c
2960
2961- Propagator:
2962 - fixed bug in shift and propagate--variable information with a negation transformation is correctly reset after backtracking
2963 - fixed bug in genvbounds propagator when applying a restart after the root node
2964
2965- Constraints:
2966 - fixed bug in varbound coefficient tightening: if a varbound constraint only contained one variable afterwards,
2967 it may have been deleted without applying the induced bound, if the change was too small, this is now forced
2968 - fixed potential wrong locks update after a varbound constraint became redundant in coefficient tightening
2969 - fixed potentially wrong cleanup of fixed variables in nonlinear constraint handler
2970 - fixed memory leak in OSiL reader when using SOS constraints
2971
2972- Solution:
2973 - improved handling of infinite values in a primal solution in quadratic and nonlinear constraints
2974 - fixed bug in computing violation and cut for certain nonlinear constraints when LP solution is slightly out of bounds
2975 - fixed debug solution check that appeared in probing mode when the objective function has changed
2976 - relaxed a too strong assert concerning solutions close to the objective limit
2977
2978@section RN400 SCIP 4.0.0
2979*************************
2980
2981Features
2982--------
2983
2984- Introduced support for partial or infeasible user solutions, which SCIP tries to complete/repair heuristically
2985- implemented linear time methods for (weighted) median selection for joint arrays of various types
2986- added adaptive solving behavior of SCIP based on solving phases and heuristic transitions, if enabled via `solvingphases/enabled`
2987- can now solve relaxations within probing
2988- in case of multiple relaxators the best solution is saved instead of the last one
2989- added write callback for reader_bnd
2990- added possibility to use a reference value for advanced analysis of the tree search. If a finite reference value
2991 (an objective value in original objective space) is passed via misc/referencevalue, SCIP keeps track of the
2992 number of nodes exceeding the reference value and the number of early backtracks -- path switches in the tree when
2993 a child node with lower bound smaller than the reference value was available.
2994- added reading capabilities for partial solutions with extension *.mst
2995- new global shift off all random seeds (randomization/randomseedshift) and unification of all existing random seeds
2996- use new macros SCIPdebugMsg(), SCIPsetDebugMsg(), SCIPstatDebugMsg() at all places where it makes sense
2997- new random number generator in pub_misc.h
2998- add check whether variables have been released when freeing SCIP
2999- a print callback can now be specified for user expressions
3000
3001- LP Solutions:
3002 - will now enforce relaxation solution instead of lp or pseudosolution if lowerbound is better and the whole lp is included in the relaxation
3003 - new feature solution polishing to improve integrality of LP solutions
3004
3005- Constraints:
3006 - new constraint handler for cardinality constraints
3007 - added interval-evaluation of sine and cosine
3008 - allow to create constraints of constraint handlers that don't need constraints
3009 - New constraint handlers cardinality and components
3010
3011- Conflicts:
3012 - implement a storage for conflicts to have more control over active conflicts
3013 - Improved conflict analysis through central conflict pool and dual ray analysis for primal infeasible LPs; can now analyze dual
3014 unbounded rays of primal infeasible LPs
3015
3016- Presolving:
3017 - New presolvers that disaggregate SOC constraints and reformulate QP's by adding KKT conditions
3018 - new presolving step for variables contained in a single quadratic constraint with proper square coefficients
3019 - add new presolving step to disaggregate second order cone constraints
3020 - new presolving method presol_qpkktref to add the KKT conditions of a QP
3021 - implemented and extended stuffing presolving in linear constraint handler
3022 - new components constraint handler which replaces the components presolver; it searches for independent subproblems
3023 and solves small ones as sub-SCIPs during presolve, larger ones are solved alternatingly during the main solving process
3024 - new presolving timing FINAL: presolving methods with this timing are only called once after all other presolvers with timings
3025 FAST, MEDIUM and EXHAUSTIVE are finished; during this timing only reductions are allowed that are self-contained, e.g.,
3026 fixing all variables and deleting all constraints of an independent component; note that reductions found in this timing
3027 do not trigger a new presolving round
3028
3029- Separation and Cuts:
3030 - can now separate perspective cuts for indicator constraints
3031 - add sepa_convexproj, a separator which projects onto convex relaxation and build gradient cuts at the projection
3032 - add sepa_gauge, a separator which computes an interior point of a convex relaxation and performs a binary search in the segment joining
3033 the interior point and the point to separate until it finds a point in the boundary of the feasible region where to build a gradient cut
3034 - changed handling of coupling constraints in cons_indicator; the cuts will not be added to the pool, but are separated by default
3035 - concurrent solving mode that allows to run multiple SCIP instances, that share solutions and global variable bounds, in parallel
3036 - Revised pseudo random number generation and introduced central random seed for all plugins
3037
3038- Heuristics:
3039 - new Graph induced neighborhood search (GINS) primal heuristic that uses neighborhoods
3040 based on distances in the variable constraint connectivity graph.
3041 In addition, the heuristic supports a rolling horizon-like procedure to solve auxiliary problems
3042 for neighborhoods with increasing distance from the starting neighborhood.
3043 - new primal heuristic LP face that tries to find an integer solution inside the optimal LP face.
3044 - new heuristic that tries to complete partial solutions
3045 - the subnlp heuristic now gives ownership of a found solution to the heuristic that constructed the starting point, if any;
3046 as a consequence, MIP heuristics may now be shown more frequently for having found a solution when solving MINLPs, even
3047 though the solutions required an additional NLP solve
3048 - new multistart heuristic for NLPs
3049
3050- Propagator:
3051 - add prop_nlobbt, a nonlinear optimization-based bound propagator solving two convex NLP relaxations for each variable
3052 - nodes can now be postponed; currently, this can only be triggered by BEFORELP propagation callbacks
3053
3054- Statistic:
3055 + Extended statistic output displayable via the interactive shell
3056 + new statistic computed: `Root LP Estimate` that shows the root LP best-estimate with every pseudo-cost update
3057 + added leaf statistics about LP objective limit|feasible|infeasible leaves to the statistics output and
3058 to the callable library: SCIPgetNObjlimLeaves(), SCIPgetNFeasibleLeaves(), SCIPgetNInfeasibleLeaves()
3059 + next to the number of found solution, also the number of new best solutions is now printed for each heuristic
3060 (and relaxation solutions) in the statistics in the `Primal Heuristic` section.
3061
3062Performance improvements
3063------------------------
3064
3065- Extended the presolving timings by an additional timing FINAL for self-contained reductions
3066- Randomized tie-breaking in different parts of the code to reduce performance variability
3067- use connectedness information of the clique table to speed up the clique partitioning algorithm
3068- knapsack approximation algorithms use linear-time weighted median selection instead of sorting
3069- improved greedy solution in SCIPsolveKnapsackApproximatelyLT() for the flow cover separation
3070- reduce performance variability by using random numbers as tie-breaker for external branching candidates
3071
3072- Heuristics:
3073 - adjusted most Large Neighborhood Search heuristics such that they collect their variable fixings first in an array,
3074 and only create and populate a sub-SCIP if enough variables will be fixed.
3075 - reduce performance variability by using a small perturbation in the undercover heuristic
3076 - 1-opt heuristic can now be repeatedly executed as long as new incumbents are found
3077
3078- Constraints:
3079 - Improved and extended stuffing inside of linear constraint handler
3080 - Changed handling of coupling constraints in cons_indicator
3081 - SCIP supports constraint compression for problem copies; constraint compression denotes the immediate
3082 removal of fixed variables from constraint data at creation time to reduce memory requirements.
3083
3084- Propagation:
3085 - rewrote the propagate-and-cut-and-price loop so that successful propagations with DURINGLPLOOP timing, bound changes found by separation,
3086 and new primal solutions now trigger a new round of node solving, starting with propagation; improved tuning of propagation and heuristic timings
3087 - tuned propagation methods of several constraint handlers
3088 - make more use of SCIPmarkConsPropagate() to mark constraints for propagation and improved the internal handling of marked constraints
3089 - improve propagation of absolute-value expression in the case that the sign of the argument is fixed
3090
3091Interface changes
3092-----------------
3093
3094### New and changed callbacks
3095
3096- Concurrent SCIP:
3097 - extended interface to support concurrent solving mode
3098
3099- Constraint Handlers:
3100 - new optional callback `CONSENFORELAX` to enforce a relaxation solution, see \ref CONS
3101 - `CONSINITLP` callback now has a new parameter `infeasible`, which is a pointer to store whether infeasibility
3102 was detected while building the initial LP relaxation
3103
3104### Deleted and changed API methods
3105
3106- setting a parameter to a non-valid value now produces an error message instead of a warning
3107- bound reader uses angle bracket around variable names
3108- the parameters of SCIPlpiChgObj(), SCIPlpiSetBase(), SCIPlpiSetState(), SCIPlpiSetNorms() have been declared as const
3109- SCIPapplyHeurSubNlp() can now return the solution found by the sub-NLP heuristic
3110
3111- Random:
3112 - methods SCIPrandomGetInt() substitutes SCIPgetRandomInt() (marked to be deprecated)
3113 - methods SCIPrandomGetReal() substitutes SCIPgetRandomReal() (marked to be deprecated)
3114 - methods SCIPrandomPermuteArray() substitutes SCIPpermuteRandomArray() (marked to be deprecated)
3115 - methods SCIPrandomPermuteIntArray() substitutes SCIPpermuteRandomIntArray() (marked to be deprecated)
3116 - method SCIPrandomGetSubset() substitutes SCIPgetRandomSubset() (marked to be deprecated)
3117
3118- Conflict Analysis:
3119 - added parameters `conftype` and `iscutoffinvolved` to SCIPinitConflictAnalysis()
3120 that indicate the type of the conflict and whether the current cutoff bound is used or not
3121
3122- Constraint Handlers:
3123 - added parameter `infeasible` to SCIPinitlpCons()
3124
3125- Copying:
3126 - added parameters `fixedvars`, `fixedvals`, `nfixedvars` to SCIPcopyVars()
3127 - added parameters `fixedvars`, `fixedvals`, `nfixedvars` to SCIPcopyOrigVars()
3128 - renamed parameter `success` to `valid` in SCIPgetConsCopy()
3129
3130- Hashmap and Hashtable:
3131 - removed function SCIPcalcHashtableSize() since not required anymore for `SCIP_HASHTABLE` and `SCIP_HASHMAP`
3132 - based on the initial size `SCIP_HASHTABLE` and `SCIP_HASHMAP` choose an appropriate size internally to allow insertion of that
3133 many elements without resizing
3134 - `SCIP_MULTIHASH` behaves like the old `SCIP_HASHTABLE` and SCIPcalcMultihashSize() should be used as replacement for
3135 SCIPcalcHashtableSize()
3136
3137- Nonlinear Relaxation:
3138 - added parameter `curvature` to SCIPcreateNlRow()
3139
3140- Parameters:
3141 - the following new methods return a bool indicating whether the given value is valid for the parameter instead of printing a warning
3142 message and returning an error code if the value is invalid
3143 - renamed method SCIPcheckBoolParam() to SCIPisBoolParamValid()
3144 - renamed method SCIPcheckLongintParam() to SCIPisLongintParamValid()
3145 - renamed method SCIPcheckCharParam() to SCIPisCharParamValid()
3146 - renamed method SCIPcheckStringParam() to SCIPisStringParamValid()
3147 - renamed method SCIPcheckRealParam() to SCIPisRealParamValid()
3148 - in param.c/h: the new methods return a bool whether the given value is valid for the parameter instead of printing a warning message
3149 and returning an error code if the value is invalid
3150 - rename SCIPparamCheckBool() to SCIPparamIsValidBool()
3151 - rename SCIPparamCheckString() to SCIPparamIsValidString()
3152 - rename SCIPparamCheckChar() to SCIPparamIsValidChar()
3153 - rename SCIPparamCheckLongint() to SCIPparamIsValidLongint()
3154
3155- Primal Heuristics:
3156 - added parameter `initialseed` to SCIPcreateDiveset()
3157 - introduced new type `SCIP_HEURTIMING` for primal heuristic timing masks
3158 - changed type of parameter `timingmask` from unsigned int to `SCIP_HEURTIMING` in SCIPincludeHeur(), SCIPincludeHeurBasic()
3159
3160- Relaxators:
3161 - new parameter `includeslp` for SCIPincludeRelax() and SCIPincludeRelaxBasic()
3162 to indicate whether relaxation includes all linear rows and can be enforced
3163
3164- Reoptimization:
3165 - rename method SCIPgetReopSolsRun() to SCIPgetReoptSolsRun()
3166
3167- Solutions:
3168 - added parameter `completely` to SCIPtrySol(), SCIPtrySolFree(), SCIPcheckSol() to check all constraints when
3169 printing violations
3170
3171- Variables:
3172 - removed SCIPvarGetLbAtIndex() and added SCIPgetVarLbAtIndex()
3173 - removed SCIPvarGetUbAtIndex() and added SCIPgetVarUbAtIndex()
3174 - removed SCIPVarGetBdAtIndex() and added SCIPgetVarBdAtIndex()
3175 - removed SCIPvarWasFixedAtIndex() and added SCIPgetVarWasFixedAtIndex()
3176 - Removed method SCIPvarGetNBinImpls()
3177
3178### New API functions
3179
3180- added functions for concurrent solving mode (see concurrent.h, concsolver.h)
3181- SCIPcreateNlpiProb(), SCIPupdateNlpiProb() and SCIPaddNlpiProbRows() to create and update a nonlinear relaxation
3182- SCIPgetNObjlimLeaves(), SCIPgetNFeasibleLeaves(), SCIPgetNInfeasibleLeaves() for statistics output
3183 about LP objective leaves
3184- SCIPcheckCopyLimits() which can be used to check that enough time and memory is left to run a sub-SCIP after
3185 subtracting time and memory used by the main-SCIP and SCIPcopyLimits() which copies these limits accordingly and disables
3186 all other limits (need to be set by the plugin, if needed)
3187- SCIPcopyLargeNeighborhoodSearch() in heuristics.h that supports compressed copying and two kinds of problem copy: the MIP-relaxation or
3188 a 1-1 problem copy (by copying the constraints and not the LP relaxation)
3189- SCIPsolveProbingRelax() to solve a relaxation within probing
3190- SCIPgetLastStrongbranchingLPSolstat() to query the LP statuses after strong branching on a variable
3191- SCIPinitializeRandomSeed()
3192- SCIPswapReals() to swap two real values
3193- SCIPgetNNZs() to get the number of active non-zeros in the transformed/presolved problem
3194
3195- Debug Messages:
3196 - SCIPprintDebugMessage(), SCIPsetPrintDebugMessage(), SCIPstatPrintDebugMessage() that output debug messages and also print the
3197 subscip depth; the first two output via the message handler; also added macros SCIPdebugMsg(), SCIPsetDebugMsg(), SCIPstatDebugMsg()
3198 - SCIPdebugMsgPrint()/SCIPsetDebugMsgPrint() that output a message without `[debug]` prefix via the message handler (compare SCIPdebugPrintf())
3199
3200- Solution:
3201 - SCIPisDualSolAvailable() to query the dual solution availability
3202 - SCIPlpiSetIntegralityInformation() to improve SoPlex' solution polishing
3203
3204- Constraints:
3205 - library methods SCIPcopyConsCompression(), SCIPcopyOrigConsCompression() that accept an array of variables that are immediately
3206 fixed in the copy. Alternatively, local instead of global bounds can be used for compression.
3207 - library methods SCIPenableConsCompression(), SCIPisConsCompressionEnabled(), SCIPcopyConsCompression(), SCIPcopyOrigConsCompression()
3208 - SCIPgetIntVarXor() to access integer variable of XOR constraints
3209 - SCIPcreateConsCardinality() to create a cardinality constraint
3210 - SCIPcreateConsBasicCardinality() to create a basic cardinality constraint
3211 - SCIPchgCardvalCardinality() to changes cardinality value of cardinality constraint (i.e., right hand side of cardinality constraint)
3212 - SCIPaddVarCardinality() to add a variable to a cardinality constraint
3213 - SCIPappendVarCardinality() to append a variable to a cardinality constraint
3214 - SCIPgetNVarsCardinality() to get the number of variables in a cardinality constraint
3215 - SCIPgetVarsCardinality() to get the array of variables in a cardinality constraint
3216 - SCIPgetCardvalCardinality() to get the cardinality value of a cardinality constraint (i.e., right hand side of cardinality constraint)
3217 - SCIPgetWeightsCardinality() to get the array of weights of a cardinality constraint
3218 - SCIPgetLinvarMay{Decrease,Increase}Quadratic() to get index of a variable in linear term of quadratic constraint that may be decreased
3219 without making any other constraint infeasible
3220
3221- Parameters:
3222 - add SCIPparamIsValidInt() and SCIPparamIsValidReal() to param.c/h
3223 - add missing functions SCIPisIntParamValid() and SCIPisRealParamValid() to scip.c/h
3224
3225### Command line interface
3226
3227- new command line parameter `-v` to print detailed build options
3228
3229### Interfaces to external software
3230
3231- Interfaces for Python and Java are, among others, now available via http://www.github.com/scip-interfaces
3232- Revised documentation of the SCIP C-API to group methods more comprehensively by topics
3233- dropped support for Ipopt < 3.11
3234- Additional I/O-functionalities for debugging and logging in SCIP and in the AMPL interface
3235- updated CppAD to 20160000
3236- for users of the ampl interface, the display/logfile option has been added to set the name of a
3237 file to write the SCIP log to (additionally to stdout)
3238
3239- LP Interfaces:
3240 - SCIP uses the lpi_spx2 interface by default
3241 - Improved Gurobi interface that can handle ranged rows (requires Gurobi >= 7.0.2)
3242 - the CPLEX LPI now also compiles with CPLEX 12.7.0.0
3243
3244### Changed parameters
3245
3246- setting a value for a fixed parameter will no longer return with an error, if the new value equals the one to which the parameter is fixed
3247- changed value of parameter `separating/clique/cliquedensity` to 0.0 such that the separator always constructs a dense clique table
3248 which proved to be faster on the benchmarks MMM and stableset.
3249- parameters `misc/permutationseed`, `misc/permuteconss` and `misc/permutevars` changed to `randomization/permutationseed`,
3250 `randomization/permuteconss` and `randomization/permutevars`
3251- parameters `conflict/useinflp` and `conflict/useboundlp` are now of type char (before bool)
3252- all parameters of the components presolver (starting with `presolving/components/`) are now parameters of the components
3253 constraint handler (starting with `constraints/components/`)
3254
3255### New parameters
3256
3257- class randomization
3258- `branching/sumadjustweight` to adjust branching scores by adding a sum epsilon in order to keep score differences
3259 near zero, which are otherwise completely disregarded (they are adjusted to at least sum epsilon)
3260- `concurrent/∗ ` and `parallel/∗ ` for configuring the concurrent solving mode
3261- `constraints/cardinality/branchbalanced` to decide whether to use a balanced branching scheme in the enforcing of cardinality
3262 constraints
3263- `constraints/cardinality/balanceddepth` to set the maximal depth until balanced branching is turned off
3264- `constraints/cardinality/balancedcutoff` to determine that balanced branching is only used if the branching cut off value
3265 w.r.t. the current LP solution is greater than a given value
3266- `constraints/indicator/sepaperspective` to turn on separation of perspective cuts for indicator constraints
3267- `constraints/indicator/sepapersplocal` to decide whether local cuts can be used for perspective cuts for indicator constraints
3268- `constraints/quadratic/projectedcuts` to enable convex quadratics to generate gradients cuts at the
3269 projection of the point onto the region described by the constraint, which is supporting
3270- `lp/solutionpolishing` to enable LP polishing only at the root LP or always
3271- `misc/referencevalue` to pass a reference value for further analysis of the tree search, see also in `features`
3272- `presolving/qpkktref/addkktbinary` to allow the presence of binary variables for the KKT update
3273- `presolving/qpkktref/updatequadbounded` to add the KKT conditions to QPs only if all variables are bounded
3274- `presolving/qpkktref/updatequadindef` to add the KKT conditions to QPs only if the quadratic matrix is indefinite
3275- `randomization/lpseed` to set the initial seed of the LP solver
3276- `solvingphases/enabled` to activate adaptive behavior during the solution process; several further parameters
3277 in the solvingphases-section to control how to switch the parameters and whether a restart should be performed between the phases.
3278
3279### Data structures
3280
3281- new `SCIP_REGRESSION` data structure in pub_misc.h to incrementally compute a best-fit line through pairs of observations
3282- add maximum branch-and-bound tree depth constant `SCIP_MAXTREEDEPTH` (replaces SCIPgetDepthLimit() and SCIPtreeGetDepthLimit())
3283- new files heuristics.c/heuristics.h to collect methods that are frequently used by heuristics
3284- merged dive.c/pub_dive.h with heuristics.c/heuristics.h, removed dive.c/pub_dive.h
3285- separated header pub_misc.h from repeated methods for sorting and (weighted) median selection;
3286 those are also available in separate headers pub_misc_sort.h
3287 and pub_misc_select.h, but included into pub_misc.h
3288
3289Unit tests
3290----------
3291
3292- New unit testing system built on the Criterion framework
3293
3294Build system
3295------------
3296
3297### Makefile
3298
3299- All makefiles in `examples/` and `applications/` have been updated.
3300- `make.project` defines a variable `SCIP_VERSION` containing the SCIP version number
3301- revise sub-makefiles for MSVC on MinGW
3302- make shared libraries aware of their dependencies
3303- sub-makefile for CrayXC systems added
3304
3305- Places:
3306 - All objective files are now placed in `obj/static` or `obj/shared`, depending on `SHARED=false` or `SHARED=true`, respectively.
3307 - All internal and external libraries are placed in `lib/static` and `lib/shared`, the include files are in `lib/include`.
3308 - The binaries now contain an rpath to the SCIP directory, such that shared libraries are found.
3309
3310- Linking:
3311 - link binary to shared libs when compiling with `SHARED=true`
3312 - External projects (including make.project) can use the makefile variable LINKCXXSCIPALL or LINKCCSCIPALL to link all SCIP libraries.
3313 - Building with `SHARED=true` automatically generates the combined library libscipsolver.so for easier linking
3314
3315- Targets:
3316 - Running `make help` lists all makefile options.
3317 - `make install` copies now all header files
3318 - new target `dll` to build Windows dlls with MSVC
3319 - rename `dll` target to `windowslib`
3320
3321Fixed bugs
3322----------
3323
3324- fixed bug in event system: bound change events of the new focus node must be processed, even if the bound
3325 is the same as at the last focus node
3326- avoid numerically unstable (multi-)aggregations
3327- fixed bug in XML reader concerning comments
3328- the AMPL interface now writes a solve status (solve_result_num) into the .sol file
3329- in the cmpres.awk (allcmpres.sh) output, the counts in the time column are now with respect to the
3330 whole set of processed instances (as with fail and solv), while before it was with respect to the
3331 set of instances where no solver failed (eval set); thus, now proc = fail + time + solv.
3332- writing of solutions or parameters to a file now works also with the message handler set to quiet
3333- ignore lower and upper bound tightenigs beyond +/-infinity during solving
3334- time limit of SCIP-infinity is converted to LPI-infinity when setting it
3335- fix LP activity of a row that has been modified
3336
3337- Propagation:
3338 - fixed possible segmentation fault in genvbounds propagator
3339 - fixed bug with sorting of propagators in presolving: the order can be changed by calling probing; thus, there is a copy of the
3340 propagators, which is sorted by presolving priority
3341 - added missing capturing and releasing mechanism in genvbounds propagator
3342 - fix wrong propagation of product expressions
3343
3344- Constraints:
3345 - fixed wrong representation of SOC constraints in NLP
3346 - fixed a few issues within redundant constraint detection of (specialized) linear constraint handlers
3347 - fixed issue in reader_opb concerning writing of fixed variables contained in no constraints
3348
3349- Memory:
3350 - fixed memory bug in `SCIP_DIGRAPH`
3351 - improved counting of memory consumption by using more block memory and counting all allocated memory
3352 - fix memory leaks in TSP example
3353 - return `SCIP_ERROR` when a memory exception is caught in SoPlex (was `SCIP_LPERROR`)
3354 - fixed memory leak in OSiL reader
3355
3356- Objective:
3357 - fixed bug while changing the objective value of an original value after transforming the problem
3358 - fixed bug with solutions from previous runs not satisfying an objective limit
3359 - SCIPisObjIntegral() now works correctly in `SCIP_STAGE_PROBLEM`
3360
3361- Heuristics:
3362 - fixed two bugs in heur_indicator: use improvesols parameter now and update pointer to indicator constraint handler
3363 - fix wrong NLP representation of logic-or constraints in the dual value heuristic
3364 - correct handling of implicit integer variables with fractional solution value in simplerounding heuristic
3365 - fixed bug in heur_octane with uninitialized ray direction
3366
3367@page RN32 Release notes for SCIP 3.2
3368
3369@section RN321 SCIP 3.2.1
3370*************************
3371
3372Features
3373--------
3374
3375- new `force` parameter in (root)redcost propagator to run the propagator also with active pricers
3376
3377Performance improvements
3378------------------------
3379
3380- do not transfer solutions to original space, if SCIP is being freed
3381- modified implication graph analysis of SOS1 constraint handler; a new component allows to deduce zero fixings of variables
3382- made SOS1 constraint handler specific diving selection rule faster for the case that the SOS1 constraints do not overlap
3383- improved disjunctive cuts by the `monoidal cut strengthening` procedure of Balas and Jeroslow
3384
3385Examples and applications
3386-------------------------
3387
3388- several improvements of SCIP-Jack (STP application): extended presolving for STP variants, STP-specific branching
3389 rule, dual heuristic to generate initial LP relaxation
3390 SCIP-Jack is now competitive with problem specific state-of-the-art solvers on several well-known STP variants,
3391 e.g., the (rooted) prize-collecting Steiner tree problem.
3392- MultiObjective application renamed to PolySCIP; several improvements: better command line argument processing,
3393 overhaul of much of the source code, installation via CMake
3394
3395Interface changes
3396-----------------
3397
3398- made debug solution functionality thread safe (see debug.h for further information)
3399
3400### Deleted and changed API methods
3401
3402- add SCIPcomputeHyperplaneThreePoints() to compute a hyperplane containing three given 3-dimensional points
3403- SCIPsolveLinearProb() now uses a 1-dimensional matrix representation
3404
3405### Command line interface
3406
3407- added interactive shell command `display finitesolution` to print solution with infinite fixings removed,
3408 added reference to that method to `display solution` output if there are infinite fixings
3409- new interactive shell command `write history` to write the command line history (only when compiled with Readline)
3410
3411### Interfaces to external software
3412
3413- significantly improved Python interface to support user callbacks as well as linear and quadratic expressions
3414
3415### New parameters
3416
3417- `constraints/sos1/branchingrule` to decide whether to use neighborhood, bipartite, or SOS1 branching (this parameter
3418 replaces the old parameters `constraints/sos1/neighbranch`, `constraints/sos1/bipbranch`, and `constraints/sos1/sos1branch`)
3419- `constraints/sos1/depthimplanalysis` to limit the number of recursive calls of implication graph analysis
3420- `constraints/sos1/perfimplanalysis` to perform an implication graph analysis to deduce variable fixings and
3421 additional SOS1 constraints (this parameter replaces the old parameter `constraints/sos1/updateconflpresol`)
3422- `misc/transsolorig` for transfering transformed solutions to the original space (default: true)
3423- `propagating/rootredcost/onlybinary` to propagate root reduced costs of binary variables only
3424
3425### Data structures
3426
3427- renamed MIP matrix structure to `SCIP_MATRIX`
3428- changed the numeric values for `PRESOLTIMING` flags
3429
3430Build system
3431------------
3432
3433### Makefile
3434
3435- new target `dll` to build Windows dlls with MSVC
3436- add new compiling flag OPENSOURCE to allow/forbid the usage of third party software
3437
3438Fixed bugs
3439----------
3440
3441- fixed wrong objective sense when copying the original problem
3442- fixed a bug in merge step of cliques during clean up phase; method did not correctly handle infeasibility in the case of multiple
3443 variable-negation pairs
3444- fixed a previously untreated case in the linear cons simplification where coefficients only differ by slightly more than an epsilon
3445- fixed bug in parsing emphasis parameters which formerly led to completely wrong results
3446- fixed bug in the computation of the Wilcoxon test
3447- do not use the relative and absolute gap limit if no primal solution has been found so far
3448- fixed bug in conflict.c with wrong reset of bounds used
3449- fixed bug with transferring solutions to new runs (need to recompute objective before checking)
3450- fixed issue with infinite values when checking cuts for redundancy
3451- fixed library problems on Windows operating systems
3452
3453- Variables:
3454 - fixed wrong check when computing cuts for factorable quadratic functions bound tightening of a single variable
3455 - fixed wrong handling of loose variables in OBBT
3456 - fixed freeing of hash for binary variables
3457 - fixed bug during the computation of branching points for continuous variables which are almost fixed to +/- SCIPinfinity()
3458 - treated the case of integer variables as intermediate variables in the process of obtaining the active variable for a
3459 given binary variable
3460
3461- LP:
3462 - fixed a bug in dive.c that occurred when lpsolvefreq was set to 1; after a cutoff, the solution values of the
3463 linked LP solution might have become invalid
3464 - do not analyse an infeasible LP for conflicts during diving mode when LHS/RHS of rows were changed
3465 - use LPi infinity when reverting bound changes in conflict analysis
3466
3467- Heuristics:
3468 - fixed bug in heur_simplerounding in connection with relaxators
3469 - fixed bug in feaspump heuristic where last solution candidates were not updated correctly
3470 - fixed bug with infinite shift values in heur_shifting
3471 - fixed bug in shiftandpropagate heuristic: the heuristic did not correctly handle intermediate, global bound changes of the selected variable
3472 after its tentative fixing led to a cutoff.
3473
3474- Propagator:
3475 - (root) reduced cost propagators are not run anymore when doing branch-and-price,
3476 since they may install upper bounds on variables which might interfere with the
3477 pricing (they may be enabled again by their force parameters)
3478 - fixed too hard assertion in pseudoobj propagator
3479 - fixed a bug in shiftandpropagate where column positions after sorting are now correctly linked to their variables after sorting
3480 - fixed potential memory leak in genvbound propagator
3481
3482- Presolving:
3483 - fixed inconsistency in knapsack constraint handler data during presolving
3484 - fixed some problem with reoptimization when the problems are infeasible or have been solved in presolving
3485 - fixed endless loop in knapsack constraint handler when continuous variables change their types to binary during presolving
3486 - squares of binary variables might not have been replaced by the binary variable itself in presolve,
3487 if the variable was originally general integer and only became binary during presolve (due to bound tightening)
3488 - fixed bug in dive.c avoiding a check of constraints in the presence of indicator constraints
3489
3490- Constraints:
3491 - fixed numerical problems in computation of cuts for bivariate functions in quadratic constraint handler
3492 - fixed bug in quadratic constraint handler when computing lifted-tangent inequalities
3493 - fixed bug in nonlinear constraint handler when replacing a violated nonlinear constraint leads to an infinite
3494 - fixed bug in SOS1 constraint handler with inconsistent data structure after restart
3495 - fixed wrong handling of negated variables in bound tightening procedure of SOS1 constraint handler
3496 - fixed bug in simple fixing heuristic of SOS1 constraint handler
3497 - fixed two bugs in pseudoboolean constraint handler with wrong sorting of and constraints
3498 - fixed issue: constraints being parallel to objective function (after restart) sometimes led to wrongly stating infeasible
3499 - fixed bug during coefficient tightening in varbound constraint handler
3500 - handle cutoffs in cons_indicator detected by infeasible inequalities
3501 - fixed late change of type of slack variables in cons_indicator, if the bounds are not integral
3502 - fixed initsol and exitsol of cons_indicator, if problem has already been solved
3503 - fixed bug in cons_indicator with changing type of slackvariable
3504
3505@section RN320 SCIP 3.2.0
3506*************************
3507
3508Features
3509--------
3510
3511- added reoptimization feature for optimization problems with changed objective function or tighter feasible region
3512- the original problem can now be permuted directly after reading (if `misc/permutationseed` has value >= 0)
3513- added methods to compute strongly connected components with Tarjan's Algorithm
3514- added method to propagate implications of SOS1 variables
3515- convex quadratic contraints can now generate gradient cuts which are supporting to the feasible region
3516- SoPlex interface can now (re)store dual steepest edge weights
3517- extended expression parsing to support power, realpower and signpower operators; started support for user-defined operators
3518 in expression trees/graphs
3519- possibility to set a soft time limit which becomes active only after the first primal solution was found
3520- added matrix module for getting access to the internal mixed inter linear problem matrix
3521- better handling of large values returned by the LP solver
3522- added more checks to SCIP{alloc,realloc,duplicate}BufferArray() to handle overflows properly
3523- new plugin for reoptimizing a sequence of optimization problem that differ in the objective function, e.g., sequences arising from
3524 column generation
3525- new plugin `compr` for rearranging the search tree, currently this only works on the reoptimization tree
3526- moved assertions in comparison methods from scip.c to set.c
3527
3528- Constraints:
3529 - we can now upgrade quadratic constraints with one bilinear term to SOC constraints
3530 - we can also upgrade general quadratic constraints with a single negative eigenvalue to SOC constraints
3531
3532- Branching:
3533 - tighter reliability notions introduced for reliability branching, based on pseudo-cost relative errors
3534 and comparing candidates with the best pseudo-candidate using a 2-sample student-T test. These methods
3535 are used in disjunction with the existing reliability notion that uses a fixed number as reliability
3536 threshold for every variable before turning off strong-branching. This means, the classical method
3537 must be turned off by setting parameters minreliable and maxreliable to 0. The behavior is
3538 controlled through several parameters.
3539 - new distribution branching rule to base decisions on row activity (normal) distribution over domain space
3540 - can now output information for BAK: Branch-and-bound Analysis Kit
3541 - new score in hybrid reliability pseudocost branching that prefers nonlinear variables when solving MINLPs
3542 - new branching rule multaggr which allows to branch on general disjunctions defined by fractional multi-aggregated variables
3543 - new branching rules for SOS1 constraints for branching on a neighborhood or a complete bipartite subgraph of
3544 the conflict graph. In addition to variable domain fixings, it is sometimes also possible to add complementarity
3545 constraints to the branching nodes. This results in a nonstatic conflict graph, which may change dynamically
3546 with every branching node.
3547 - new branching rule nodereopt to reconstruct the tree after changing the objective function
3548
3549- Reader:
3550 - the MPS reader can now read semi-integer variables, they are handled by creating bound disjunction constraints
3551 - the MPS reader can now handle objective constants given as (the negation of) the RHS of the objective row
3552
3553- Separation:
3554 - obbt propagator applies now additional separation and propagation in order to learn stronger and more bound tightenings
3555 - extended probing mode to allow separation and objective coefficient changes
3556 - improved separation procedure of SOS1 constraint handler, including bound (clique) cuts and implied bound cuts
3557 - new disjunctive cut separator for SOS1 constraints
3558 - new edge-concave cut separator for quadratic constraints
3559
3560- Presolver:
3561 - Improved coordination of presolvers. There are three timings for presolvers now, FAST, MEDIUM and EXHAUSTIVE.
3562 Each presolving callback can specify one or more of these timings in which it will be called later.
3563 Within a presolving method, the current timing can be checked and the algorithms to be performed selected based on
3564 the timing. In one presolving round, first all presolving methods with timing FAST are called, sorted by priority.
3565 If they found enough reductions, a new round is started, otherwise, all presolving methods with timing MEDIUM are
3566 called. Again, with enough reductions, a new presolving round is started, too few reductions lead to running
3567 the EXHAUSTIVE presolvers. Similar to the delay concept used before, we are not neccessarily running all EXHAUSTIVE
3568 presolvers but stop as soon as one of them found enough reductions, starting a new presolving round immediately.
3569 - new presolving components for SOS1 constraints, including bound tightening and clique extension
3570 - new presolver tworowbnd for improving variable bounds and detecting redundant constraints added
3571 - new presolver dualagg for aggregating single up-/downlocked variables by a binary variable added
3572 - new presolver implfree for aggregating implied free variables added
3573 - new presolver redvub which can detect redundant variable upper bound constraints added
3574 - new presolver stuffing for fixing of singleton continuous variables added
3575
3576- Heuristic:
3577 - improved clique and variable bound heuristics
3578 - new heuristic distribution diving that bases its score function on the changes regarding solution density
3579 - variable histories can be transferred between sub-SCIPs solved by LNS heuristics and the component presolver
3580 and the main SCIP to reuse this information.
3581 - new heuristic heur_indicator that tries to make partial solutions with indicator constraints feasible. It also
3582 tries to improve them (or external solutions) by a one-opt local search.
3583 - new heuristic (heur_bound) which fixes all integer variables to their lower/upper bounds and solves the remaining LP
3584 - modified diving heuristics to handle SOS1 constraints
3585 - new primal heuristic for reoptimization 'ofins': objective function induced neighborhood heuristic
3586 - new heuristic for reoptimization which constructs solutions based in the changes between the objective function and the optimal
3587 solution before changing the objective function
3588
3589- Statistic:
3590 - extended variable branching statistics in the interactive shell by sample variance of unit gains
3591 - extended statistic output of interactive shell by more information on diving heuristic behavior
3592
3593Performance improvements
3594------------------------
3595
3596- improved treatment of nonlinearities in hybrid reliability pseudo cost branching
3597- using sparsity information of the SoPlex LP
3598
3599- Constraints:
3600 - improved vartype upgradability from continuous to implicit variables in cons_linear.c, depending on their objective coefficients
3601 - improved propagation of SOS1 constraint handler using the information from a conflict
3602
3603- Heuristics:
3604 - zi rounding heuristic uses buffer data structures, thereby decreasing total memory usage of SCIP
3605 - adjusted (hard) diving heuristics to solve fewer LPs. LP's are resolved only if a parameter-defined
3606 percentage of the variable bounds changed through domain propagation or at a predefined frequency.
3607 - some of the diving heuristics additionally consider indicator variables and SOS1 variables as candidate variables and try to
3608 make these constraint types feasible before passing a rounded solution to SCIPtrySol()
3609
3610- Presolving:
3611 - new presolving/propagation algorithm using the gcd for ranged rows and equations in cons_linear
3612 - added presolving levels (FAST, MEDIUM and EXHAUSTIVE) to allow better balancing of presolvers
3613
3614- Separation:
3615 - improved separation procedure of SOS1 constraint handler
3616 - improved separation procedure for convex quadratic constraints
3617
3618Examples and applications
3619-------------------------
3620
3621- two new applications for multi-objective optimization (PolySCIP) and the Steiner Tree Problem in Graphs
3622- new application for solving Steiner tree problems: SCIP-Jack can handle both the classical Steiner tree problem in graphs
3623 and 10 of its variants
3624
3625Interface changes
3626-----------------
3627
3628### New and changed callbacks
3629
3630- new callback function `SCIP_DECL_CONSGETDIVEBDCHGS` to provide
3631 constraint handler method to suggest dive bound changes during the generic diving algorithm, see type_cons.h for details
3632- new callback `SCIP_DECL_DIVESETGETSCORE` to implement scoring function to guide diving
3633
3634### Deleted and changed API methods
3635
3636- avoid potential comparisons of different infinity values by adjusting the LP solution value
3637- SCIPintervalSign(), SCIPintervalAbs(), SCIPintervalMax(), SCIPintervalMin(), SCIPexprgraphGetNodePolynomialMonomialCurvature(),
3638 and SCIPexprgraphTightenNodeBounds() need an infinity value to decide whether an interval is empty or not
3639- SCIPgetFeasibilityQuadratic() and SCIPgetActivityQuadratic() returns now a `SCIP_RETCODE` and needs an additional `SCIP_Real*` to
3640 store the result
3641- methods which support statistical tests in pub_misc.h, SCIPstudentTGetCriticalValue(), SCIPcomputeTwoSampleTTestValue() etc.
3642- SCIPsolveLinearProb() solves a linear problem of the form Ax=b for a regular square matrix A
3643- Added parameter `freesubscip` to SCIPapplyProximity()
3644
3645- Data structures:
3646 - Renamed method SCIPdigraphGetSuccessorsDatas() to SCIPdigraphGetSuccessorsData()
3647 - Renamed method SCIPdigraphGetNodeDatas() to SCIPdigraphGetNodeData()
3648 - Renamed method SCIPdigraphSetNodeDatas() to SCIPdigraphSetNodeData()
3649
3650- Constraint Handlers:
3651 - Renamed method SCIPconshdlrGetPropTimingmask() to SCIPconshdlrGetPropTiming()
3652 - new method SCIPconshdlrSetPropTiming()
3653 - Removed method SCIPconshdlrIsPresolvingDelayed()
3654 - Removed method SCIPconshdlrWasPresolvingDelayed()
3655 - SCIPmakeSOS1sFeasible() based on solution values, fixes variables to zero to turn all SOS1 constraints feasible
3656 - removed `delay(presol)` parameter from SCIPinclude{Conshdlr,Presol,Prop}() and added `(presol)timing` parameter
3657 - new parameter `presoltiming` for method SCIPpresolCons()
3658 - SCIPvarIsSOS1() returns whether some variable is involved in an SOS1 constraint
3659 - SCIPgetConflictgraphSOS1() gets conflict graph of SOS1 constraints
3660 - Added parameter `presoltiming` to SCIPpropCumulativeCondition()
3661 - Removed parameter `delaypos` from SCIPsetConshdlrPresol()
3662 - Added parameter `presoltiming` to SCIPsetConshdlrPresol()
3663 - Removed parameter `delaypos` from SCIPincludeConshdlr()
3664 - Added parameter `presoltiming` to SCIPincludeConshdlr()
3665 - Added parameter `consgetdivebdchgs` to SCIPincludeConshdlr() to provide a divebdchg-callback for the constraint handler
3666 to include
3667
3668- Branching Rules:
3669 - Added parameter `forcestrongbranch` to SCIPselectVarStrongBranching()
3670 - Added parameter `executebranching` SCIPexecRelpscostBranching()
3671 - Added parameters `ndomredsdown` and `ndomredsup` to SCIPgetVarStrongbranchWithPropagation()
3672
3673- LP and Cutting Planes:
3674 - Added parameters `inds` and `ninds` to SCIPgetLPBInvRow(), SCIPgetLPBInvCol(), SCIPgetLPBInvARow(), SCIPgetLPBInvACol(), and
3675 SCIPcalcStrongCG()
3676 - Added parameters `maxweight`, `weightinds`, `nweightinds`, and `rowlensum` to SCIPcalcMIR()
3677
3678- Variables:
3679 - SCIPvarGetNodeSOS1() returns node of SOS1 variable in the conflict graph
3680 - SCIPnodeGetVarSOS1() returns SOS1 variable associated to some given node in the conflict graph
3681 - Removed method SCIPvarGetNBinImpls()
3682
3683- Presolving:
3684 - Removed parameter `delaypos` from SCIPincludePresolBasic()
3685 - Added parameter `presoltiming` to SCIPincludePresolBasic()
3686 - Removed parameter `delaypos` from SCIPincludePresol()
3687 - Added parameter `presoltiming` to SCIPincludePresol()
3688 - Removed parameters `presoldelay` and `presoltiming` from SCIPincludePresol()
3689 - Removed parameters `presoldelay` and `presoltiming` from SCIPsetPropPresol()
3690
3691- Misc:
3692 - Added parameter `isequation` to SCIPaddClique()
3693 - Removed parameter `writeimplications` from SCIPwriteCliqueGraph()
3694 - Removed method SCIPallocBufferSize()
3695 - Removed method SCIPduplicateBufferSize()
3696 - Removed method SCIPreallocBufferSize()
3697 - Removed method SCIPfreeBufferSize()
3698 - Removed method callback SCIPdialogExecConflictgraph()
3699
3700### New API functions
3701
3702- started support for user-defined operators in expression trees/graphs (see SCIPexprCreateUser()),
3703 interface will likely change again in future SCIP versions
3704- new methods for mixed inter linear matrix access (see pub_matrix.h) added
3705- SCIPcomputeArraysIntersection() to compute the set intersection of two ordered arrays
3706- SCIPcomputeArraysSetminus() to compute the set difference of two ordered arrays
3707- SCIPcutGetLPActivityQuot() in pub_cutpool.h to get the potion of LP's where this cut was sharp in an optimal basis.
3708- SCIPpresolGetTiming(), SCIPpresolSetTiming(), SCIP{conshdlr,prop}GetPresolTiming(), and SCIP{conshdlr,prop}SetPresolTiming()
3709- SCIPdigraphSetNSuccessors() sets the number of successors of some digraph node to a given value
3710
3711- Diving:
3712 - SCIPcreateDiveset() to add a diveset to a heuristic. Heuristics may have multiple divesets under different names
3713 - SCIPperformGenericDivingAlgorithm() that performs diving with periodic LP resolve according to the diveset argument.
3714
3715- Constraints:
3716 - new setter function SCIPsetConshdlrGetDiveBdChgs() in scip.h to set dive bound change callback for this constraint handler
3717 - SCIPaddDiveBoundChange() to add a diving bound change to the diving bound change storage of SCIP together with the information if this is a
3718 bound change for the preferred direction or not, to be used by constraint handlers inside the getDiveBdChgs-callback
3719 - SCIPchgCoefLinear() and SCIPdelCoefLinear() to modify linear constraint during problem creation
3720
3721- Memory:
3722 - BMSallocClearBlockMemoryArray()/SCIPallocClearBlockMemoryArray() and
3723 BMSallocClearBufferMemoryArray(), SCIPallocClearBufferArray() to allocate arrays that are initialized to 0
3724 - SCIPbuffermem() to get buffer memory;
3725
3726- Sort:
3727 - added new sorting functions SCIPsortRealRealRealBoolBoolPtr(), SCIPsortDownRealRealRealBoolBoolPtr()
3728 - added new sorting functions SCIPsortIntIntIntReal(), SCIPsortDownIntIntIntReal(), SCIPsortRealIntInt(), SCIPsortDownRealIntInt()
3729
3730- Param:
3731 - SCIPwriteParam() to write a single parameter to a file
3732 - SCIPcheckParam{Bool,Char,...}() to check whether a parameter value is within the feasible domain
3733
3734- Quadratic:
3735 - SCIPchgLhsQuadratic(), SCIPchgRhsQuadratic(), SCIPchgLinearCoefQuadratic(), SCIPchgSquareCoefQuadratic(),
3736 and SCIPchgBilinCoefQuadratic() to modify quadratic constraints during problem creation
3737 - SCIPgetFeasibilityQuadratic() and SCIPgetActivityQuadratic() to get the feasibility and activity of a quadratic constraint in a given solution
3738 - SCIPaddSquareLinearization(), SCIPaddSquareSecant(), SCIPaddBilinLinearization() and SCIPaddBilinMcCormick()
3739 in cons_quadratic.h to compute linear under- and overestimation for bilinear and quadratic terms
3740
3741### Command line interface
3742
3743- extended variable branching statistics and statistic output in the interactive shell (see Statistic section)
3744- submenu for setting `vbc` settings renamed to `visual`
3745- at the end of a command line run the best solution can now be output in the orignal space
3746
3747### Interfaces to external software
3748
3749- in the AMPL interface, variable and constraint attributes (flags) can now be set via suffixes, where 0 (unset) stands
3750 for the default, 1 for TRUE and other values for FALSE; see SCIPcreateVar() and SCIPcreateCons() for their meaning;
3751 for variables, `initial` and `removable` are recognized;
3752 for constraints, `initial`, `separate`, `enforce`, `check`, `propagate`, `dynamic` and `removable` are recognized
3753- the AMPL interface now passes an initial guess, if specified, as a solution (that will be checked for feasibility) to SCIP
3754
3755### Changed parameters
3756
3757- rowrepswitch set to 2.0, so row representation is activated if LP has at least 2 times more rows than columns
3758- one can now set emphasis parameters at the beginning of a settings file; it should start with `emphasis:` and
3759 the contain the emphasis string, e.g., `emphasis: feasibility` or `emphasis: heuristics off`.
3760
3761- Renamed parameters:
3762 - `vbc/filename` to `visual/vbcfilename`
3763 - `vbc/realtime` to `visual/realtime`
3764 - `vbc/dispsols` to `visual/dispsols`
3765
3766### New parameters
3767
3768- added parameter to switch pseudo cost update in diving heuristics (enabled by default)
3769- `branching/relpscost/confidencelevel` to set the confidence level to be used by statistical tests
3770- `branching/relpscost/higherrortol` to define the highest reliability threshold for relative error based reliability
3771- `branching/relpscost/lowerrortol` to define a lower reliability threshold for relative error based reliability
3772- `branching/relpscost/nlscoreweight` for weight of nonlinear score when branching on MINLPs
3773- `branching/relpscost/usedynamicconfidence` to use a dynamic confidence level based on the amount of
3774 strong-branching simplex-iterations compared to the overall simplex iterations (default is FALSE)
3775- `branching/relpscost/usehyptestforreliability` to enable strong branching decisions based on a 2-sample student-T test of all prior
3776 pseudo-cost observations between the best pseudo-candidate and the candidate for which to decide whether strong-branching should be applied
3777- `branching/relpscost/userelerrorreliability` to enable relative error based reliability
3778- `branching/relpscost/skipbadinitcands` for skipping strong-branching candidates whose estimated gain
3779 is significantly worse than the one of the locally best (sb or pseudo) candidate
3780- `constraints/linear/multaggrremove` to perform multi-aggregations in linear constraint handler only if the constraint can be removed afterwards
3781- `constraints/linear/rangedrowpropagation` to disabled newly implemented propagtion algorithm for ranged rows and equations
3782- `constraints/quadratic/advanced/interiorcomputation` to select the way of computing and interior point for gauge cuts
3783- `constraints/quadratic/gaugecuts` to enable convex quadratics to generate gradients cuts which are supporting
3784- `constraints/soc/generalsocupgrade` to allow general quadratics to be upgraded to soc
3785- `constraints/SOS1/addcomps` to add local complementarity constraints to the branching nodes (can be used in combination
3786 with neighborhood or bipartite branching)
3787- `constraints/SOS1/addbdsfeas` to define a minimal feasibility value for local bound (clique) inequalities in order to be
3788 added to the branching node
3789- `constraints/SOS1/addcompsdepth` to define the maximal depth for adding complementarity constraints
3790- `constraints/SOS1/addcompsfeas` to define a minimal feasibility value for local complementarity constraints in order to be
3791 added to the branching node
3792- `constraints/SOS1/autocutsfromsos1` to automatically switch to separating bound cuts from SOS1 constraints if the SOS1
3793 constraints do not overlap
3794- `constraints/SOS1/autosos1branch` to switch to SOS1 branching if the SOS1 constraints do not overlap
3795- `constraints/SOS1/conflictprop` to define whether to use conflict graph propagation
3796- `constraints/SOS1/bipbranch` to branch on a complete bipartite subgraph of the conflict graph
3797- `constraints/SOS1/boundcutsdepth` to define the node depth of separating bound (clique) cuts
3798- `constraints/SOS1/boundcutsfreq` to define the frequency for separating bound (clique) cuts
3799- `constraints/SOS1/boundcutsfromgraph` to define whether to separate bound (clique) inequalities from the conflict graph
3800- `constraints/SOS1/boundcutsfromsos1` to define whether to separate bound (clique) inequalities from SOS1 constraints
3801- `constraints/SOS1/fixnonzero`: If neighborhood branching is used, then fix the branching variable (if positive in sign)
3802 to the value of the feasibility tolerance
3803- `constraints/SOS1/implcutsdepth` to define the node depth of separating implied bound cuts
3804- `constraints/SOS1/implcutsfreq` to define the frequency for separating implied bound cuts
3805- `constraints/SOS1/implprop` to define whether to use implication graph propagation
3806- `constraints/SOS1/maxaddcomps` to define the maximal number of complementarity constraints added per branching node
3807- `constraints/SOS1/maxboundcuts` to define the maximal number of bound (clique) cuts separated per branching node
3808- `constraints/SOS1/maxboundcutsroot` to define the maximal number of bound (clique) cuts separated per iteration in the root node
3809- `constraints/SOS1/maximplcuts` to define the maximal number of implied bound cuts separated per branching node
3810- `constraints/SOS1/maximplcutsroot` to define the maximal number of implied bound cuts separated per iteration in the root node
3811- `constraints/SOS1/maxextensions` to define maximal number of extensions that will be computed for each SOS1 constraint in presolving
3812- `constraints/SOS1/maxsosadjacency` to define that the adjacency matrix of the conflict graph is not created in presolving if
3813 the number of SOS1 variables is too large
3814- `constraints/SOS1/maxtightenbds` to define the maximal number of bound tightening rounds per presolving round
3815- `constraints/SOS1/neighbranch` to branch on a neighborhood of the conflict graph
3816- `constraints/SOS1/nstrongiter` to define the maximal number LP iterations to perform for each strong branching round
3817- `constraints/SOS1/nstrongrounds` to define the maximal number of strong branching rounds to perform for each node (only
3818 available for neighborhood and bipartite branching)
3819- `constraints/SOS1/sos1branch` to branch on a single SOS1 constraint, i.e., a clique of the conflict graph
3820- `constraints/SOS1/sosconsprop` to define whether to use SOS1 constraint propagation
3821- `constraints/SOS1/strthenboundcuts` to define whether to strengthen bound (clique) cuts in case bound variables are available
3822- `constraints/SOS1/updateconflpresol` to update the conflict graph during the presolving procedure
3823- `display/allviols` to print all violated constraints of the best solution during checksol in the scip shell
3824- `heuristics/indicator/improvesols` that turns on the improvement of external solutions by one-opt
3825- `heuristics/∗diving/lpresolvedomchgquot` to determine the percentage of changed domains since previous LP to trigger
3826 an LP resolve [default: 0.15] (* stands for eight diving heuristics to support this feature)
3827- `heuristics/∗diving/lpsolvefreq` to determine the frequency for resolving LP's during the execution of
3828 this heuristic [default: 1, use 0 for a dynamic setting based on the number of domain reductions]
3829 (* stands for eight diving heuristics to support this feature)
3830- `heuristics/shiftandpropagate/binlocksfirst` to set if binaries without locks should be preferred in ordering
3831- `heuristics/shiftandpropagate/maxcutoffquot` to select a maximum percentage of allowed cutoffs before stopping the heuristic (default is 0.0)
3832- `heuristics/shiftandpropagate/selectbest` to trigger if shiftandpropagate should select the best candidate in every round
3833 (set to FALSE for static order) (default is FALSE)
3834- `limits/autororestart` for triggering an automatic restart after this many nodes, or -1 for no auto restart [default is -1]
3835- `limits/softtime` to set a soft time limit (active only after first primal solution was found)
3836- `misc/allowobjprop` to allow objective function propagation
3837- `misc/allowdualreds` to allow dual reductions
3838- `misc/outputorigsol` to control whether at the end of a command line run the solution should be output in the orignal space
3839- `numerics/checkfeastolfac` to scale feasibility tolerance when checking the feasibility of best found solution
3840 after the solving process finished (e.g., checksol in scip shell)
3841- `separating/cutselrestart` for cut selection during restart copy process (`a`ge, activity `q`uotient) [default is `a`]
3842- `separating/cutselsubscip` for cut selection for sub SCIPs (`a`ge, activity `q`uotient) [default is `a`]
3843- `separating/disjunctive/maxconsdelay` to delay separation of disjunctive cuts if number of SOS1 constraints is larger than predefined value
3844- `separating/disjunctive/maxdepth` to define the node depth of separating disjunctive cuts
3845- `separating/disjunctive/maxinvcuts` to define the maximal number of disjunctive cuts investigated per iteration in a branching node
3846- `separating/disjunctive/maxinvcutsroot` to define the maximal number of disjunctive cuts investigated per iteration in the root node
3847- `separating/disjunctive/maxrank` to define the maximal permissible rank of a disjunctive cut that could not be scaled to integral coefficients
3848- `separating/disjunctive/maxrankintegral` to define the maximal permissible rank of a disjunctive cut that could be scaled
3849 to integral coefficients
3850- `separating/disjunctive/maxrounds` to define the maximal number of separation rounds of disjunctive cuts in a branching node
3851- `separating/disjunctive/maxweightrange` to define the maximal valid range of simplex tableau row weights
3852
3853### Data structures
3854
3855- new enum `SCIP_CONFIDENCE_LEVEL` for different levels of confidence for statistical tests.
3856- new struct `SCIP_DIVESET` that bundles options for SCIP's diving heuristics; all hard diving heuristics (those
3857 without `obj` at the beginning) include diveset and implement only the scoring callback.
3858- rename all file `*_vbc.?` to the more generic `*_visual.?`
3859- moved buffer memory handling to blockmemory/memory.?;
3860 remove files type_buffer.h, struct_buffer.h buffer.h buffer.c;
3861 removed functions SCIP*buffer*() from scip.? and replaced them by macros;
3862 redesigned buffer interface to be similar to block memory; added checks for strange sizes
3863
3864Testing
3865-------
3866
3867- added scripts and targets for testing with xpress (see Makefile section)
3868
3869Build system
3870------------
3871
3872### Makefile
3873
3874- new parameter `DELHEADERS` for `uninstall`-target: scip headers are only removed when invoking `make uninstall DELHEADERS=true`
3875- added scripts check_xpress.awk, check_xpress.sh, evalcheck_xpress.sh and check_cluster_xpress.sh and target
3876 `testclusterxpress` and `testxpress`
3877
3878Fixed bugs
3879----------
3880
3881- fixed bug in primal.c and tree.c by using SCIPinfinity() as a cutoffbound to delete child nodes
3882- fixed bug in lp.c which leads to wrong primal and dual feasibility
3883- fixed wrong handling of infinite activities and primal values in sepastore.c and lp.c
3884- fixed bug that led to an erroneous warning about the clock type
3885- fix behavior of `make install` which now sets symbolic links and short links to binaries and libraries
3886- fix bug which lead to wrong global bound tightenings in prop_genvbounds.c
3887- fix call to random generator for Windows operating systems in misc.c
3888- fixed again a bug in backward propagation of linear expressions in expression graph
3889- fixed bug in prop_symmetry.c, where an incorrect weak symmetry handling constraint got added.
3890
3891- NLP:
3892 - fixed bug in heur_nlpdiving.c: wrong counting of fix variables
3893 - fix wrong handling of `SCIP_NLPSOLSTAT_LOCALINFEASIBLE` solution status in nlp.c
3894 - fix characterization of logic or constraints in SCIP's NLP relaxation
3895
3896- Branching:
3897 - fixed wrong comparison when executing branching rule for external branching candidates
3898 - fix spatial branching on implicit integer variables
3899 - fix wrong comparisons of values larger/less than +/- SCIPinfinity() in branch.c, lp.c and sol.c
3900 - fixed problem with lpisrelax flag in probing mode when doing branch-and-price
3901
3902- Constraint Handlers:
3903 - try to handle fixings of multi-aggregated variable in cons_sos1 presolving and avoid error
3904 - fixed bug in pseudoboolean constraint handler about negated variables
3905 - fixed assert in cons_soc.c: now soc with 1 lhs variable are allowed
3906 - fixed wrong assert in cons_indicator (slack variables might be replaced by active variables that have nonzero objective)
3907 - fix late creation of auxiliary LP in cons_nonlinear.c, which lead to a segmentation fault with lpi_spx2.cpp
3908 - fixed bug in cons_abspower.c: do not generate cuts with infinity right-hand-side anymore
3909 - fixed setting of enforcement flag for constraints created by reformulation in nonlinear constraint handlers
3910 - fixed bug in cons_indicator with handling local bounds
3911
3912- Memory:
3913 - fix potential memory leak in SoPlex LP interfaces when setting invalid basis
3914 - fix potential memory leak in method SCIPgetConsCopy()
3915 - fix potential memory leak in method detectRedundantConstraints() of the knapsack constraint handler
3916
3917- Interval arithmetic:
3918 - fix handling of infinite intervals in SCIPintervalIsEmpty()
3919 - fixed bug in intervalarith.c: bivariate quadratic equations may have been solved wrongly if second variable is unbounded
3920
3921- Quadratic Constraints:
3922 - fix wrong sorting of bilinear terms in cons_quadratic
3923 - fix potentially tightening of LB/UB of a variable to +/- infinity in cons_quadratic
3924 - fixed bug in cons_quadratic.c which leads to an overflow when SCIP allocates memory for a dense matrix
3925 - fixed bug in cons_quadratic.c: do not generate linearization cuts for disabled constraints
3926 - fix missing clean phase of bilinear terms with zero coefficient in cons_quadratic.c
3927
3928@page RN31 Release notes for SCIP 3.1
3929
3930@section RN311 SCIP 3.1.1
3931*************************
3932
3933Features
3934--------
3935
3936- use clock average to reduce number of system calls via `timing/rareclockcheck` parameter
3937- added copy mechanism for conjunction constraints
3938- added revised lpi_xprs for using XPRESS as LP solver
3939
3940Performance improvements
3941------------------------
3942
3943- improved solving of LPs in OBBT propagator
3944- improved activity-delta computation and thereby propagation for linear constraints
3945- improved memory management of proximity heuristic
3946- disabled statistic timing in all subscips via new parameter `timing/statistictiming`
3947
3948Interface changes
3949-----------------
3950
3951### New and changed callbacks
3952
3953- rename array arcdatas in digraph to arcdata
3954- changes in clock type are now transferred to SoPlex
3955- corrected wrong primal bound in statistics for unbounded problems
3956- forbid to call SCIPfixVar() in `SCIP_STAGE_PRESOLVED` stage, which is not allowed since it calls SCIPchgVarLb/Ub()
3957
3958### Deleted and changed API methods
3959
3960- rename SCIPdigraphGetNodeDatas() to SCIPdigraphGetNodeData();
3961- rename SCIPdigraphSetNodeDatas() to SCIPdigraphSetNodeData()
3962- SCIPapplyProximity() has an additional parameter freesubscip, which causes the method to free
3963 the created subscip automatically at the end.
3964
3965### New API functions
3966
3967- SCIPhasPerformedPresolve() to check, e.g., whether LP duals are accessible
3968- SCIPconvertRealTo[Long]Int() to convert reals that represent integers to [long] ints.
3969- SCIPisDualfeasEQ() and related to perform checks w.r.t. to the dual feasibility tolerance
3970- SCIPdeleteSubproblemProximity() to free proximity subproblem manually as external caller
3971
3972### Command line interface
3973
3974- added dialog for writing the finite solution (calling SCIPcreateFiniteSolCopy() before writing)
3975
3976### Interfaces to external software
3977
3978- AMPL interface now returns dual multipliers if problem is an LP and presolving was turned off
3979
3980### Changed parameters
3981
3982- changed default value of parameter `heuristics/proximity/minimprove` to 0.02; previous value was 0.25
3983- changed default value of parameter `heuristics/proximity/usefinallp` to FALSE
3984
3985### New parameters
3986
3987- `timing/rareclockcheck` to call the system time less frequently, based on the current average time interval
3988 between two calls to SCIPsolveIsStopped(); the default value is FALSE
3989- `timing/statistictiming` to enable/disable all timers for statistic output of SCIP; the default value is TRUE
3990
3991### Data structures
3992
3993- renamed MIP matrix structure to `SCIP_MATRIX`
3994- changed the numeric values for `PRESOLTIMING` flags
3995
3996Build system
3997------------
3998
3999### Makefile
4000
4001- added Makefile support for cygwin 64 Bit
4002- allow to turn off block and buffer memory by the makefile parameters NOBLKMEM, NOBUFMEM, NOBLKBUFMEM;
4003 also remove the now superfluous makefiles for noblkmem, nobufmem, noblkbufmem
4004
4005Fixed bugs
4006----------
4007
4008- fixed wrong conversion of reals representing negative integer values
4009- in debug mode, SCIP checks that no NaN's are introduced in SCIPsolSetVal()
4010- fixed bug 697 (and 699), calling SCIPsolve() after the problem was already solved and SCIPfreeSolve() was called now
4011 does nothing anymore
4012- added support for character `#` in variable names in old non-linear CIP format (i.e., names without `<` and `>`)
4013- fixed bug 702, removed too hard assert when casting too big values into `SCIP_Longint`
4014- branching for continuous variables with unbounded intervals now takes `branching/clamp` into account
4015- forbid aggregations with scalar smaller feastol or larger 1/feastol
4016- fixed bug 683, not recognizing errors/segfaults especially in free stage of SCIP by improving the check scripts
4017- fixed bug where quieting a message handler also disabled writing to files other than stdout
4018- fixed bug 708, special case of implications led to a fixing
4019- fixed bug, variable bounds detected wrong infeasibility
4020- another bug fix when computing the original variable sum of a given variable in SCIPvarGetOrigvarSum()
4021- fixed setting solution value of multi-aggregated var in xml-solution case
4022- fixed bug changing the variable type of an negated variable
4023- fixed numerical troubles in SCIPcreateFiniteSolCopy()
4024- fixed bug in SCIPpermuteProb(): if called before transforming the problem, data structures were not initialized yet
4025- fixed bug in aggregation procedure if two variables were of non-binary type but for one of the variables
4026 SCIPvarIsBinary() returned true
4027- treat activities of pseudo solutions as invalid when containing positive and negative infinity contributions
4028- fixed bug in GMI example: fractionality of slack variable is now computed correctly
4029- fixed LP interface of CPLEX: functions getBInv* return the correct sign of the coefficients.
4030- fixed bug in SCIPpermuteProb(), when called in transformed stage and non-active constraints exist
4031
4032- Dual:
4033 - use dual feasibility tolerance for comparisons regarding reduced costs
4034 - fixed bug in prop_dualfixing: don't fix variables to infinite values during solving
4035 - fixed sign of the dual multipliers returned by AMPL interfaces for maximization
4036
4037- Objective and Time Limit:
4038 - fixed wrong output of status when an objective limit was imposed but not reached yet
4039 - fixed the rare case that branching was performed even though strong branching found global bound changes leading to
4040 an infeasible/objlimit LP
4041 - fixed bug that objective limit was not reset correctly during SCIPfreeTransform() for maximization problems
4042 - fixed bug that hitting the time limit while solving a pure LP and then continuing the solving process lead to
4043 not solving the LP, but always creating a single child node until maximum depth is reached
4044
4045- Heuristic:
4046 - fixed bug leading to an incorrect dual bound when solving probing LPs within a DURINGPRICINGLOOP heuristic
4047 - fixed bug in proximity heuristic which attempted to enter diving mode even at nodes without a constructed LP
4048 - fixed wrong pseudo cost updates during diving heuristic execution after backtracking
4049 - fixed bug in heur_oneopt: avoid bound violations if shift value is negative due to infeasibilities
4050 - fixed bug that reaching a solution limit by beforenode heuristics lead to disregarding the current node if the
4051 optimization process was restarted later
4052 - fixed bug in trysol heuristic not saving the best solution in maximization problems
4053
4054- Presolve:
4055 - fixed bug in presolving of abspower constraints that lead to wrong variable locks
4056 - allow to call SCIPmarkConsPropagate() in INITPRESOLVE stage
4057 - fixed bug in components presolver with handling of dual fixable variables: unboundedness was not detected,
4058 better handle components with single variables by dual fixing propagator
4059 - issues in component solving by presol_components do not lead to stopping the overall process, anymore, the component
4060 is just disregarded
4061
4062- Memory:
4063 - fixed bug with freeing problem: need to reset objective limit
4064 - fixed memory leaks in case of erroneous parsing of constraints, e.g., non-linear constraints
4065 - fixed missing memory allocation for node data in digraphs
4066
4067- Constraints:
4068 - fixed bug in cons_quadratic which leads to wrong min/max activities
4069 - removed wrong break in cons_pseudoboolean
4070 - fixed bug in cons_varbound.c using the wrong constraint side for updating an upper bound
4071 - fixed bug in presolve of cons_nonlinear: wrong constraint upgrades may have been performed due to outdated bound
4072 information in expression graph
4073 - fixed bug in cons_setppc, wrongly aggregating variables if dual-presolving was disabled
4074 - fixed bug in cons_sos1: locks and events were not initialized if constraint was added to transformed problem
4075 - fixed bug in cons_setppc with dual presolving disabled
4076 - corrected copy of disjunction constraints
4077
4078- Reading:
4079 - allow to read numbers like `42856.` in lp-format
4080 - fixed bug(?) in reader_mps: variables are now written in columns section even of they occur in no constraint
4081 and have an objective coefficient of 0 (otherwise, CPLEX and Gurobi cannot read the file)
4082 - fixed bug with reading `>=1` indicator constraints in LP-files
4083 - fixed bug in reader_lp which created two indicator constraints with the same name to trigger an equality
4084 - fixed bug when reading indicator constraints for linear constraints (equations/ranged rows) from MPS files
4085
4086@section RN310 SCIP 3.1.0
4087*************************
4088
4089Features
4090--------
4091
4092- added breadth first search node selection
4093- new node selection rule UCT which balances exploration and exploitation by considering node visits
4094- added possibility to not set a cutoff bound in the LP solver (can be enabled by setting `lp/disablecutoff` to TRUE)
4095- added missing debugging solution check for cliques
4096- added a data pointer to each node of the `SCIP_DIGRAPH`
4097- SCIPgetVarCopy() will now copy the original bounds when called for an original variable
4098- added upgrade of continuous variables to implicit variables for linear equations even if the coefficient is
4099 not equal to 1
4100- probing supports implicit binary variables
4101- added scaling to computation of relative interior point in SCIPcomputeLPRelIntPoint()
4102
4103- Solution:
4104 - added two methods to iterate over a sparse solution (`SCIP_SPARSESOLUTION`), see pub_misc.h
4105 - it is now possible to add an offset for the original problem instance, all original solutions will be initialized with
4106 this value and updated, when the offset is changed
4107 - extended and corrected dual feasibility checks for LP solution (controlled by parameter `lp/checkdualfeas`)
4108
4109- Cuts and Separation:
4110 - the rank of cuts is now stored and taken into account to improve numerical stability
4111 - added possibility to separate a cutpool w.r.t. a given solution (instead of LP-solution)
4112
4113- Branching:
4114 - new branching rule `cloud branching` that considers several alternative LP optima
4115 - additional vbc output added: branching information is printed earlier and also for nodes which were cut off
4116 - added support for strong branching with domain propagation in full strong and reliability pseudo cost branching
4117 - added strong branching with domain propagation support: in SCIPstartStrongbranch(), support for propagation can
4118 be enabled (uses the probing mode, some overhead compared to standard strong branching), after that
4119 SCIPgetVarStrongbranchWithPropagation() can be used to perform strong branching on a variable with previous domain
4120 propagation; similar to probing, valid bounds for variables are collected
4121 - strong branching with propagation can be enabled in fullstrong and relpscost branching rule
4122 - added possibility to store pricing norms of the LP solver (in addition to basis information) to speed up LP solving
4123 after a backtrack, e.g. in probing or strong branching with domain propagation
4124 - a pricer can now return that no further pricing should be done but rather early branching, even if it added variables
4125
4126- LP interface:
4127 - SoPlex (>= 1.7.0.5) can compute condition number of current basis matrix via LP interface
4128 - LPI files (lpi*.[h|c]) all moved from src/scip to src/lpi
4129
4130- Constraints:
4131 - added propagation method to cons_xor relying on Gaussian elimination, which can also produce feasible solutions
4132 - added first implication detection in cons_linear
4133 - cons_indicator can now try to construct feasible solutions from a cover
4134 - added possibility to forbid upgrading of linear constraints
4135 - new initial constraints are now added to the LP before solving a probing LP
4136 - first implementation of parsing for nonlinear constraints in CIP format
4137 - added upgrade from varbound constraints to set-packing constraints
4138 - added upgrade from bounddisjunction constraints to set-packing/logicor constraints
4139 - cumulative constraint handler adds disjunctive constraints (cumulative with capacity 1) for all jobs which cannot
4140 be processed in parallel
4141 - added new clique extraction algorithm for linear constraints
4142 - the slack variables of indicator constraints can now be scaled
4143 - added redundancy check of sides of ranged row varbound constraint
4144 - added coefficient tightening for ranged row varbound constraint
4145 - XOR constraint handler can add two extended formulations (flow/asymmetric, parameter `addflowextended/addextendedform`)
4146 - added multi-aggregation for binary variables with at most two uplocks and two downlocks, which emerge from set-
4147 partitioning or set-packing constraints
4148 - added upgrade from quadratic constraints to set-packing constraints
4149 - generalized the linking constraint handler
4150
4151- Reader:
4152 - can now read and write CIP-files with (multi-)aggregated variables
4153 - all readers now take the global parameters `reading/dynamic{conss|cols|rows}` and `reading/initialconss` into account
4154 - added reader_pbm, which writes the constraint-variable incidence matrix in pbm format (possibly scaled to given size)
4155 - reader_osil can now read SOS1 and SOS2 constraints
4156 - reader_lp and reader_mps are now able to write and-constraints in form of their (weak/strict) relaxation
4157 - added reading capability to GAMS reader (if compiling with GAMS=true, requires a GAMS system)
4158 - added capability of writing SOS1/2 constraints to GAMS reader (introduces extra variables and equations)
4159
4160- Heuristic:
4161 - new primal heuristics dual value
4162 - new LNS heuristic called `proximity`, which solves a problem in which a local branching constraint replaces the
4163 objective function which in turn is treated as additional constraint
4164 - new LP-based rounding heuristic (heur_randround) whose randomized rounding is biased towards the LP solution value;
4165 the heuristic uses the probing mode of SCIP to generate conflict clauses on the fractional variables
4166
4167- Presolving:
4168 - added new dual presolving for setppc-constraints
4169 - changed dualfix presolver to propagator such that dual fixing can also be applied during repropagation of the root node
4170 - added full-dual presolving step in setppc constraint handler
4171 - dual solution can now be displayed for pure LPs when no presolving was performed
4172 - added clique presolving for xor constraints
4173 - added presolving using pairs of variable bound constraints that use the same variables
4174 - added more presolving to cons_indicator, checking whether indicator/slack variables are aggregated
4175 - added presolve.{c,h} which should be used for all preprocessing mechanisms executed from within SCIP, corresponding to
4176 solve.{c,h} and also for presprocessing methods which can be called from different plugins or from the core to avoid
4177 code doubling
4178 - return error if variable should be fixed to infinity after presolving (LP-solvers do not handle this consistently)
4179 - in verblevel `SCIP_VERBLEVEL_FULL`, the number of non-zeros will be output for the original and presolved model
4180 - new presolving step for tightening logicor constraints using implication and clique information
4181 - several new presolving steps for linear and knapsack constraints, using gcd information and many more
4182
4183- Statistic:
4184 - added average gap based on primal-dual integral to solution statistics; can be disabled via parameter
4185 `misc/calcintegral`
4186 - the statistics now include the value of the first LP solved at the root node (without cuts)
4187 - added new statistic which distinguishes between internal nodes and leaves which got processed
4188 - new section `Root Node` in statistics, listing objective value, iterations and solving time for the first LP solved
4189 at the root node as well as final dual bound of the root node and LP iterations for processing the root node
4190 (those where listed in the `Solutions` section before, named `Root Dual Bound` and `Root Iterations`)
4191
4192Performance improvements
4193------------------------
4194
4195- allow multiaggregation of binary variables
4196- shorten conflicts and deriving global boundchanges from conflicts
4197- apply lowerbound provided by pricers already during pricing loop, stop pricing if the lower bound computed by pricing
4198 already exceeds the cutoff bound
4199- improved performance of SCIPcliquelistDel(), SCIPcliquetableAdd(), SCIPcliquetableCleanup()
4200
4201- LP Solution:
4202 - strong branching LP solutions are checked for integrality
4203 - improved LP reoptimization for branch-and-price applications
4204 - improved numerical stability checks for LP solution
4205 - faster feasibility check of LP solutions (controlled by parameters `lp/checkprimfeas` and `lp/checkdualfeas`)
4206
4207- Presolver:
4208 - improved methods SCIPlpiGetBInv{Row,Col,ACol} for row representation in SoPlex LP interface
4209 - improved performance of method SCIPsolRetransform() when called during presolving with many aggregations
4210 - minor presolving performance improvements in cons_logicor.c and cons_knapsack.c
4211 - dual fixing presolver was turned into a propagator
4212 - many presolving improvements in constraint handlers
4213 - improved dual-presolving for setppc constraints in special cases
4214
4215- Constraints:
4216 - major improvements in pseudo-boolean constraint handler
4217 - performance improvement in domain propagation by marking constraints for propagation
4218 - added more constraint upgrading possibilities
4219 - improved handling of initial constraints created during solving
4220 - disabled scaling in feasibility check of nonlinear constraint handlers
4221 - conflict consisting of exactly two binary variables will be handled as set-packing constraint instead of an logicor
4222 constraint and the corresponding clique information is globally added
4223 - fasten repropagation for set-packing and -partitioning constraints
4224 - improved merging of and-constraints
4225 - disabled multi-aggregation in linear constraint handler when coefficients differ too much
4226 - improved multi-aggregation in linear constraint handler when only one variable in the aggregation has infinity
4227 contribution
4228 - added upgradability for implicit binary variable cases for linear constraints
4229
4230Examples and applications
4231-------------------------
4232
4233- new textbook Gomory mixed integer cuts example
4234
4235Interface changes
4236-----------------
4237
4238- removed all message length parameters in message.c and for printing error messages (not needed anymore)
4239
4240### New and changed callbacks
4241
4242- Domain Propagation:
4243 - added parameter `nmarkedconss` to SCIP_DECL_CONSPROP() callback which gives the number of constraints marked
4244 for propagation (these constraints are listed first in the conss array given as parameter).
4245
4246- Primal Heuristics:
4247 - Added parameter `nodeinfeasible` to SCIP_DECL_HEUREXEC() callback which states whether the current subproblem was
4248 already detected to be infeasible. In this case, the current LP solution might not respect local bounds and the
4249 heuristic must not assume that it does.
4250
4251- Variable Pricers:
4252 - Added parameter `stopearly` to callback method SCIP_DECL_PRICERREDCOST(). This boolean pointer should be used by the pricer
4253 to state whether early branching should be performed, even if new variables were added in the current pricing round.
4254
4255- Branching Rules:
4256 - new possible return value `SCIP_DIDNOTFIND` for SCIP_DECL_BRANCHEXECLP(), SCIP_DECL_BRANCHEXECPS(), and
4257 SCIP_DECL_BRANCHEXECEXT() callbacks to state that the branching rule searched, but did not find a branching.
4258
4259### Deleted and changed API methods
4260
4261- SCIPcalcMIR() takes an additional parameter sidetypes to determine which side of the rows to use
4262 (relevant for ranged rows)
4263- SCIPvarParseOriginal() and SCIPvarParseTransformed() now return the end of the parsed string
4264- SCIPgetConsCopy() now always captures the created constraint
4265
4266- Branching:
4267 - Added parameter `nfracimplvars` to SCIPgetLPBranchCands()
4268 - SCIPgetLPBranchCands() can be used to retrieve the number of implicit integer variables with fractional LP solution
4269 value via an additional pointer; the corresponding implicit integer variables can be accessed together with their
4270 fractionalities and solution values in the same way as binary and integer variables before; the arrays are sorted such
4271 that binary and integer variables precede the implicit integer variables; the method SCIPbranchcandGetLPCands()
4272 has been modified in the same way
4273
4274- LP and Cutting Planes:
4275 - Added parameter `sidetypes` to SCIPcalcMIR() to specify the specify row side type to be used.
4276 - Added parameter `cutrank` to SCIPcalcMIR() and SCIPcalcStrongCG() which stores the rank of the returned cut;
4277 via SCIProwChgRank() the rank of a cut can be changed (default rank is 0)
4278 - Added parameter `infeasible` to SCIPaddCut() which is a pointer to store whether the cut is infeasible for the
4279 local bounds.
4280 - SCIPgetLPObjval() now returns the LP value of the current (suboptimal) basis if the iteration limit is hit during LP
4281 solving (instead of -infinity); this value is not necessarily a valid dual bound and must not be used as such, but can
4282 be used as an objective estimate, e.g., if strong branching is simulated using the probing mode
4283 - removed parameter `normtype` from function SCIPcomputeLPRelIntPoint()
4284
4285- Misc:
4286 - Added parameter `lazyconss` to SCIPwriteMIP() to swith writing removable rows as lazy constraints.
4287 - Added parameter `enablepropagation` to SCIPstartStrongbranch(), which can be used to enable strong branching
4288 with domain propagation.
4289 - SCIPstartStrongbranch() has a new parameter `propagate` to enable or disable propagation support for strong branching
4290 - New method SCIPgetVarStrongbranchWithPropagation() which performs strong branching with propagation on a variable.
4291 - Added parameter `endptr` to SCIPparseVar() which stores the final string position after parsing.
4292
4293### New API functions
4294
4295- added SCIPdebugCheckConss() to the debugging mechanism and therefore created a `SCIP_SOL` (in original space) in debug.c
4296- before copying solutions to the original solution candidate storage, infinite solution values can now be removed using SCIPcreateFiniteSolCopy()
4297- SCIPsortLongPtrRealBool(), SCIPsortLongPtrRealRealBool(), SCIPsortLongPtrRealRealIntBool() and corresponding
4298 methods for sorting, insertion and deletion
4299- SCIPstoreSolutionGap() in scip.c, to store the gap when the first and last solution is found
4300- SCIPwriteCliqueGraph() which allows to write a graph with node weights for fractional variables
4301
4302- Separation:
4303 - SCIPconshdlrIncNCutsFound(), SCIPsepaIncNCutsFound() and SCIPsepaIncNCutsFoundAtNode() to increase the number of found cuts
4304 - SCIPseparateSolCutpool() to separate a cutpool w.r.t. a given solution
4305
4306- Constraint Handlers:
4307 - New method SCIPconshdlrGetStrongBranchPropTime() which returns the time used for domain propagation methods
4308 of the constraint handler during strong branching.
4309 - New method SCIPconsIsMarkedPropagate() which returns whether a constraint is marked for propagation.
4310 - New methods SCIPconsAddUpgradeLocks() and SCIPconsGetNUpgradeLocks() to increase or get the number of upgrade
4311 locks of a constraint.
4312 - New method SCIPgetNCheckConss() which returns the number of checked constraints.
4313
4314- Data structures:
4315 - New methods SCIPsparseSolGetFirstSol() and SCIPsparseSolGetNextSol() to get the first sparse solution
4316 or iterate over the sparse solutions, respectively.
4317 - New methods for the `SCIP_QUEUE` data structure in pub_misc.h to handle a (circular) queue, e.g., SCIPqueueCreate(),
4318 SCIPqueueFree(), SCIPqueueInsert(), SCIPqueueRemove(), SCIPqueueFirst(), SCIPqueueIsEmpty(), SCIPqueueNElems()
4319 - New method SCIPgmlWriteNodeWeight() to write a node section including weight to a .gml graph file.
4320 - New methods for hash tables: SCIPhashtableRemoveAll(), SCIPhashtableGetNElements(), SCIPhashtableGetLoad()
4321 - New methods in pub_misc.h to handle a resource activity, e.g., SCIPactivityCreate(), SCIPactivityFree(),
4322 SCIPactivityGetVar(), SCIPactivityGetDemand() ...
4323 - New methods for digraphs: SCIPdigraphResize() to resize the graph and SCIPdigraphSetNodeDatas() and
4324 SCIPdigraphGetNodeDatas() to set and get the data attached to the nodes.
4325
4326- Domain Propagation:
4327 - New method SCIPpropGetStrongBranchPropTime() which returns the time spent by a domain propagator during strong branching.
4328 - New methods SCIPmarkConsPropagate() and SCIPunmarkConsPropagate() to (un)mark a constraint for propagation.
4329
4330- LP and Cutting Planes:
4331 - New methods SCIPchgRowLhsDive() and SCIPchgRowRhsDive() to change left and right hand side of a row during diving.
4332 - Added parameter `cutoff` to SCIPsolveDiveLP(), SCIPsolveProbingLP(), and SCIPsolveProbingLPWithPricing()
4333 which is a pointer to store whether the diving/probing LP was infeasible or the objective limit was reached.
4334 - SCIPgetFirstLP{Dual/Lower}boundRoot() which return the value of the first LP solved at the root node
4335 - SCIPgetNRootFirstLPIterations() which returns the number of LP iterations for the first LP solved at the root node
4336 - SCIPlpiGetNorms(), SCIPlpiSetNorms() and SCIPlpiFreeNorms() for getting the LP pricing norms from the LP
4337 solver, loading them back into the solver and freeing the data
4338 - New method SCIPgetFirstLPTime() and SCIPgetNRootFirstLPIterations() to return time and iterations for the first LP solve
4339 and SCIPgetFirstLPDualboundRoot() and SCIPgetFirstLPLowerboundRoot() to return the first root LP dual and lower bound.
4340 - New method SCIPprintDualSol() which prints the dual solution for a pure LP (works only with preprocessing disabled).
4341 - New method SCIPisCutApplicable() which returns whether a cut is good enough to be applied.
4342
4343- Message Handler:
4344 - the main output routine of message.c (`bufferMessage` now handleMessage) has been rewritten: it now does not need
4345 a copy of the string to be output anymore, which makes the code much simpler (and also faster); it is passed a
4346 function pointer to the output function and uses it to directly output the (buffered) messages
4347 - New generic messagehandler output callback method SCIP_DECL_MESSAGEOUTPUTFUNC().
4348 - Removed parameter `msglength` from callback method SCIP_DECL_ERRORPRINTING().
4349 - New method SCIPmessageVPrintError() to print an error message.
4350 - Removed method SCIPmessagePrintWarningHeader().
4351
4352- Parameters:
4353 - New method SCIPparamGetCharAllowedValues() to get the allowed values for a char parameter.
4354 - New method SCIPgetParam() to get the parameter with a given name.
4355
4356- Variables:
4357 - SCIPapplyProbingVar() in prop_probing.h
4358 without deteriorating its objective value
4359 - SCIPshrinkDisjunctiveVarSet(), which takes an set of variables with corresponding bounds and boundtypes, and
4360 tries to derive global boundchanges and also to shorten this set of variables by using cliqe, implication and
4361 variable bound information
4362 - SCIPselectVarStrongBranching() to get the variable that fullstrongbranching would select
4363 - New method SCIPvarGetValuehistory() to get the value-based history of a variable.
4364
4365- Misc:
4366 - New method SCIPdoNotMultaggr() which returns whether multi-aggregation was disabled.
4367 - New method SCIPcreateFiniteSolCopy() to create a copy of a solution with infinite fixings removed.
4368 - New method SCIPadjustImplicitSolVals() which sets implicit integer variables to an integer value in the given
4369 solution without deteriorating its objective value.
4370 - New method SCIPcopyOrig() to copy the original problem. Analoguosly, use SCIPcopyOrigProb(), SCIPcopyOrigVars(),
4371 and SCIPcopyOrigConss() to copy original problem data, variables, or constraints, respectively.
4372 - New method SCIPwriteCliqueGraph() to write the clique graph in GML format into a given file
4373 - New method SCIPaddOrigObjoffset() to add an offset to the objective function.
4374 in original space and updates all orignal solutions correspondingly
4375 - New method SCIPcopyImplicationsCliques() to copy implications and cliques to a copied SCIP instance.
4376 - New method SCIPgetOpenNodesData() which returns all unprocessed nodes.
4377 - Added parameter `endline` to SCIPprintDisplayLine() to switch printing a newline symbol at the end of the line.
4378 - New method SCIPgetNLimSolsFound() returning the number of feasible primal solution respecting the objective limit.
4379
4380### Command line interface
4381
4382- allow dialog option to write clique graph
4383- dual solution values can now be obtained in the interactive shell after solving a pure
4384 LP without presolving
4385
4386### Interfaces to external software
4387
4388- new SoPlex 2.0 interface, can be enabled with `LPS=spx2`
4389- add support for SOS1 and SOS2 constraints to AMPL interface (see `interfaces/check/testset/SOS/sos?a.mod` for example)
4390- added copy of GAMS interface from COIN-OR/GAMSlinks project; GAMS-reader in SCIP can now read model instances from .gms files
4391- beta version of a python interface for the scipoptsuite is now available under interfaces/python
4392- beta version of a Java native interface is now available under `interfaces/jni`
4393
4394### Changed parameters
4395
4396- parameter `branching/scorefunction` has new value `q` for for `q`uotient branching score function
4397- replaced parameter `lp/checkfeas` by two parameters `lp/checkprimfeas` and `lp/checkdualfeas` to decide on primal and dual
4398 feasibility checks individually
4399- removed all local parameters `reading/(READER)/dynamic{conss|cols|rows}` and replaced them by global parameters
4400 `reading/dynamic{conss|cols|rows}`
4401- changed default value of parameter `numerics/dualfeastol` to 1e-7 for safer dual bounds from LP solver
4402- new possible values for parameter `heuristics/shiftandpropagate/sortkey` for sorting variables w.r.t. their norm,
4403 default changed from `u` to `v`, which means sorting downwards by violations
4404
4405- Constraints:
4406 - changed type of parameters `constraints/bivariate/scaling`, `constraints/quadratic/scaling`, `constraints/soc/scaling`
4407 from boolean to character
4408 - changed default for `constraints/{abspower,bivariate,nonlinear,quadratic,soc}/scaling` to off
4409 - changed default max coefficient for big-M constraint to be initial from 1e6 to 1e9
4410
4411- Separation:
4412 - changed default value of gomory cut separation parameter `separating/gomory/maxrank` from 0 to 3, to take also gomory
4413 cuts that could not be scaled to integral coefficients, with maximal rank 3 into account
4414 - remove parameter `separating/closecuts/relintnormtype`
4415
4416### New parameters
4417
4418- `branching/checksol` and `branching/heursbsol` to specify whether the strong branching LP solution
4419 should be checked for feasibility and whether a simple rounding heuristic should be run on this solution
4420- `branching/firstsbchild` and `branching/forceall` to specify the first child node to be
4421 investigated during strong branching (`u`p, `d`down, `a`uto) and whether always both children should be solved (only for
4422 strong branching with domain propagation, per default, the second child is not looked at when the first is infeasible)
4423- `conflict/fullshortenconflict` to decide whether we want to stop shortening a conflict set, when no
4424 global bound changes can be found anymore
4425- `conflict/maxvarsdetectimpliedbounds` to decide whether the a valid conflict of what maximal length
4426 will be used to derive global bound changes
4427- `constraints/{linear,knapsack}/detectcutoffbound` and `constraints/{linear,knapsack}/detectlowerbound`
4428 to enable/disable detection of constraint parallel to the objective function that will add an cutoffbound or an
4429 lowerbound respectively and these constraints will be prevented from entering the LP
4430- `constraints/and/upgraderesultant` to upgrade resultants of and constraints from binary to implicit binary variables, default is TRUE
4431- `constraints/abspower/scaling` and `constraints/nonlinear/scaling`
4432- `constraints/indicator/scaleslackvar` for scaling of the slack variable in indicator constraints
4433- `constraints/indicator/trysolfromcover` for trying to construct a feasible solution from a cover
4434- `constraints/linear/checkrelmaxabs` for checking linear constraints with a side of 0.0 relative to
4435- `constraints/linear/detectpartialobjective` to enable/disable the detection of sub-equations of the objective function
4436- `constraints/logicor/strengthen`, should pairwise constraint comparison try to strengthen constraints by removing superflous non-zeros?
4437- `constraints/xor/addextendedform` to add an extended formulation in XOR-constraints
4438- `constraints/xor/addflowextended` to add use the extended flow formulation in XOR-constraints
4439- `heuristics/<heurname>/lplimfac` for LNS heuristics to limit the number of LPs solved in a subproblem
4440 the maximum absolute value in the activity instead of 1.0
4441- `heuristics/shiftandpropagate/fixbinlocks` for fixing binary variables with no locks in one direction to the corresponding bound
4442- `heuristics/shiftandpropagate/collectstats` which decides whether variable statistics are collected
4443- `heuristics/shiftandpropagate/impliscontinuous` to decide whether implicit integer variables are treated as continuous variables
4444- `heuristics/shiftandpropagate/preferbinaries` and `heuristics/shiftandpropagate/stopafterfeasible`,
4445 which decide whether binaries should be shifted first and the shifting should be stopped when no violations are left
4446- `lp/disablecutoff` to toggle usage of LP cutoff bound (0: enabled, 1: disabled, 2: auto = disabled if pricers are used)
4447- `misc/calcintegral` (default TRUE) to trigger calculation of primal-dual integral
4448- `misc/finitesolutionstore` to switch whether infinite fixings should be removed from solutions before
4449 copying them to the original solution store
4450- `misc/permuteconss` and `misc/permutevars` to control whether variables and/or constraints should be permuted, if permutationseed != -1
4451- `presolving/components/feastolfactor` to increase the feasibility tolerance in all sub-SCIPs, when solving a component
4452- `propagating/obbt/conditionlimit` to discard instable LP bases
4453- `reading/(READER)/initialconss` that determines whether model constraints are initial
4454- `reading/cipreader/writefixedvars` for disabling printing of fixed variables in CIP format
4455- `reading/lpreader/aggrlinearization-ands` and `reading/mpsreader/aggrlinearization-ands` to enable/disable
4456 the printing of the weak or strict relaxation of and-constraints in LP and MPS format, respectively
4457- `reading/lpreader/linearize-and-constraints` and `reading/mpsreader/linearize-and-constraints` to
4458 allow and-constraints to be linearized when printing in LP and MPS format, respectively
4459- `separating/feastolfac` to allow dynamic decrease of relaxation feasibility tolerance depending on feasibility to applied cuts,
4460 i.e., allow relaxation solutions to have a primal infeasibility of at most this factor times the infeasibility of applied cuts
4461- `separating/gomory/sidetypebasis` to decide whether the sides of ranged rows should be determined from the basis status
4462- `separating/oddcycle/cutthreshold` to run odd cycle separation if not enough cuts have been found
4463- `separating/zerohalf/delayedcuts` to use the delayed cutpool for the zerohalf separator
4464- `write/allconss` to enable that all constraints are written
4465- `write/genericnamesoffset` when writing a generic problem to define an offset on the variable numbering
4466
4467### Data structures
4468
4469- New structure to store value-based branching and inference history (see pub_history.h).
4470- new data structure for (circular) queues (`SCIP_QUEUE`)
4471- hash tables will now increase dynamically
4472- Moved LP solver interfaces to subdirectory `src/lpi`.
4473
4474Testing
4475-------
4476
4477- added McNemar tests and Wilcoxon signed rank tests to cmpres.awk evaluation scripts
4478- added passing MEM option of testgams(cluster) target as workspace option to GAMS jobs
4479- extended test scripts by statistical tests
4480
4481Build system
4482------------
4483
4484### Makefile
4485
4486- default flag for ZIMPL is now `auto`, which means that it is built if and only if GMP is available (GMP=true)
4487- fixed make install for older Mac systems where install command does not have option -t
4488- dropped support for Ipopt < 3.10
4489
4490Fixed bugs
4491----------
4492
4493- fixed bug when adding (global) clique, implications or variable bound information in solving stage that lead to
4494 global bound changes which contradict local bounds and therefore need to be stored as pending bound changes
4495- unlinking a solution now copies solution values smaller than SCIPepsilon() avoiding some feasible solution in the
4496 transformed problem to be infeasible in the original problem
4497- fixed bug when flushing the warning buffer when SCIP is closed
4498- fixed bug when a bound change contradicts a local bound and is stored as pending, but the contradicting local
4499 bound becomes global afterwards (--> node where pending bound change is valid can be cut off)
4500- fixed statistics bug: externally given solutions and new solutions found while transforming existing ones
4501 are now listed in line `other solutions` of primal heuristics statistics
4502- fixed bug in random generators SCIPgetRandomInt() and SCIPgetRandomReal() for large intervals
4503- make sure that bound changes of negated original variables are correct
4504
4505- Branching:
4506 - fixed bug w.r.t. changing the variable branching priority beyond the problem stage
4507 - allow again branching on continuous variables with huge bounds
4508
4509- Separation:
4510 - fixed bug in sepa_cgmip computeObjWeightSize() w.r.t. equal sized rows
4511 - fixed wrong bound calculation in sepa_rapidlearning
4512 - fixed bug in flowcover separator to exclude unconstrained rows in aggregation
4513
4514- LP and Interfaces:
4515 - fixed bug that lead to resolving the LP after diving instead of restoring the buffered solution
4516 - fixed rare bug with conflict analysis and LP/LPI having different states after diving
4517 - fixed several bugs in lpi_grb
4518 - fixed wrong strong branching results in lpi_grb.c and an invalid write
4519 - fixed bug in handling max-function in ampl interface; added support for min-function
4520
4521- Presolving:
4522 - fixed bug in prop_dualfix w.r.t. to fixing of variables to infinity after presolving
4523 - fixed wrong presolving finished status which sometimes occurred when the time limit was hit during presolve
4524 - fixed bug where a limit on presolving rounds was exceeded by 1
4525 - fixed minor bugs in presolving in cons_setppc.c and cons_logicor.c
4526 - fixed minor bug in cons_linear w.r.t. disabled presolving
4527
4528- Propagators:
4529 - fixed bug in genvbounds propagator occurring when objective offset or scale changes after a restart
4530 - fixed bug in genvbounds propagator by replacing non-active variables on right-hand side after presolving
4531
4532- Readers:
4533 - fixed memory bug in reader_mps
4534 - fixed several minor bugs with handling of memory when writing aggregated variables (reader_lp, reader_mps)
4535 - fixed bug in reader_lp when writing bilinear terms (product sign was missing)
4536 - fixed bug in reading indicator constraints in mps-format
4537 - nonlinear readers now create auxiliary objective variables and constraints always as initial and not removable
4538 in order to avoid unbounded LPs due to loose variables with infinite best bound
4539
4540- Constraints:
4541 - fixed several bugs where variables or constraints were not freed correctly
4542 - do not multi-aggregate variables if the constant would be a huge value in order to avoid numerical troubles
4543 - fixed bug with infinite multi-aggregation constants
4544 - fixed output of aggregated variables in indicator constraints in lp and mps-format
4545 - improved handling of initial constraints: constraints which are initial, but added during the search to an already
4546 treated node are kept and added to the LP at every node where they are active
4547 - fixed bug in cons_superindicator concerning names of upgraded constraints
4548 - fixed bug in cons_indicator with trying to create solution in problem stage
4549 - fixed bug in cons_orbitope with fixing upper right triangle in non-root nodes
4550
4551Miscellaneous
4552-------------
4553
4554- new SCIP Optimization Suite homepages
4555
4556@page RN30 Release notes for SCIP 3.0
4557
4558@section RN302 SCIP 3.0.2
4559*************************
4560
4561Features
4562--------
4563
4564- reading erroneous CIP files can now output some indication of syntax errors
4565- can now run splint on core files
4566- cons_xor now uses the integral variable in propagation
4567- allowed to switch on/off the solution debugging
4568
4569Performance improvements
4570------------------------
4571
4572- improved SCIPlpiAdd{Cols,Rows}() in SoPlex LPi
4573
4574Examples and applications
4575-------------------------
4576
4577Interface changes
4578-----------------
4579
4580### New API functions
4581
4582- SCIPmarkColNotRemovableLocal() and SCIPmarkRowNotRemovableLocal() to forbid removal of an column/row
4583 from the LP in the current node
4584- SCIPmessageVPrintError()
4585
4586### Command line interface
4587
4588- can now output the solutions in the solution pool in the interactive shell
4589
4590### Interfaces to external software
4591
4592- updated Mosek LP interface to compile with Mosek 7
4593
4594Fixed bugs
4595----------
4596
4597- fixed bugs in solution counting
4598- fixed fieldtypes in sorting template
4599- fixed bug concerning the userinterrupt flag, which was not reset
4600- fixed solution collection when counting solutions
4601- fixed bug with storing original solutions
4602- fixed bug with infinite multi-aggregation constants
4603- fixed bug that removing reverse implication did not reset closestvblpcount
4604- fixed bug that duplicate solutions stopped copying of solutions to original solution candidate store
4605- forbid branching on variables with huge bounds; such huge values cannot be enumerated with fixed precision
4606 floating point arithmetics
4607- fixed bug that Ipopt's error message was not fully shown due to exiting before the message handler buffer was emptied
4608- unlinking a solution now copies solution values smaller than SCIPepsilon() avoiding some feasible solution in the
4609 transformed problem to be infeasible in the original problem
4610- allow to add columns (rows) with nonzero indices beyond current number of rows (columns) in SoPlex LPi
4611- updated get.ASL script to cope with broken ftp access to netlib server
4612
4613- Memory:
4614 - fixed bugs with freeing C++ object data for problem and variables
4615 - fixed memory leak in lp.c (probably never occurred so far since array was not used)
4616 - fixed bug in sepa_zerohalf.c where the maxcuts(root) parameters led to an invalid memory allocation call
4617
4618- LP:
4619 - fixed assert in solve.c with branched status and LP reached the objective limit
4620 - fixed bug in heur_oneopt.c and heur_clique.c which was caused by side-effects when calling SCIPconstructLP(); when
4621 adding new variables in this method (e.g. adding new variables needed for a relaxation), this changes the variables
4622 array of SCIP
4623 - fixed problem that diving did not save status for infeasible LPs
4624 - fixed bug in SCIPlpComputeRelIntPoint() with wrong iteration limit and with wrong recompution
4625 - fixed bug that old LP size was not updated for deadend if no LP was solved
4626
4627- Expressions:
4628 - fixed issues with ungraceful termination when encountering unsupported expression operands in AMPL interface
4629 - fixed bug in backward propagation of linear expressions in expression graph
4630
4631- Propagation:
4632 - fixed potential performance issue with tree depth always assumed to be zero when propagating in probing mode
4633 - fixed bug in prop_vbound w.r.t. creation of variables during the search
4634 - fixed several bugs in propagation of cons_xor: need to take integral variables into account
4635 - fixed bug in cons_abspower.c handling infinity values in propagation
4636 - fixed bug in cons_and.c when a constraint was not correctly propagated which led to wrong dual-presolve reductions
4637 - fixed bug in cons_abspower: wrong infinity check when propagating bounds
4638
4639- Presolving:
4640 - fixed bug that the number aggregated variables were not counted in presol_inttobinary.c
4641 - fixed bug in presol_domcol: locks are now checked to see whether rounding was forbidden for a variable
4642
4643- Reader:
4644 - fixed bug in reader_gms.c w.r.t. writing nonlinear expressions with polynomials with constants
4645 - fixed bugs in parsing bounds from CIP-files, in reader_gms and AMPL interface
4646 - fixed bug when reading a mps formated file with a missing bound in the bound section
4647
4648- Constraints:
4649 - fixed bug in cons_bounddisjunction with satisfied literal of multi-aggregated variable
4650 - fixed bug in upgrade method of cons_soc
4651 - fixed issue with negated variables in cons_xor.c
4652 - fixed several asserts in cons_xor presolving
4653 - fixed bug in cons_xor.c calling method on null pointer row
4654 - fixed bug using a too hard comparison on the objective-infeasible-decision in constraint enforcement
4655 - fixed possible cycling in enforcement of nonlinear constraints due to too early removal of newly added cuts from LP
4656 - fixed bug wrongly removing constraints locally while counting
4657 - fixed bugs in cons_bivariate.c when the nonlinear function is not differentiable on the boundary of the domain
4658 - fixed bug in cons_indicator.c:SCIPmakeIndicatorFeasible() with handling fixed variables
4659 - fixed bug in cons_integral: check integrality of implicit integer variables when a solution is checked for feasibility
4660 - fixed bug in Undercover with `pseudo-`quadratic constraints
4661 - fixed bug with quadratic constraints not being upgraded
4662 - fixed bug in intervalarith.c: bivariate quad. equations may have been solved wrongly if second variable is unbounded
4663
4664- Separation:
4665 - fixed bug in sepa_zerohalf.c not copying the displays to the subscip, but still changing a display parameter there
4666 - fixed iteration limit determination in sepa_closecuts
4667 - fixed bug in sepa_closecuts: need to make sure that variable values of separation point satisfy bounds
4668 - fixed bugs in sepa_oddcylce: number of arcs have to be adjusted, handle implicit binary variables,
4669 fixed bug in heuristic separation method, fixed asserts
4670 - fixed wrong bound calculation in sepa_rapidlearning
4671
4672@section RN301 SCIP 3.0.1
4673*************************
4674
4675Features
4676--------
4677
4678- added delayed cutpool which only gets separated if the sepastore is empty after a separation round
4679- sepa_cgmip can now take the objective row into account
4680- added possibility to run clang compiler
4681- statistics now include output on number of solutions that respect objective limit
4682
4683Performance improvements
4684------------------------
4685
4686- also copying active tight cuts from the delayed cut pool when calling SCIPcopyCuts()
4687- sort genvbounds only when root node is finished; apply more often
4688
4689Examples and applications
4690-------------------------
4691
4692Interface changes
4693-----------------
4694
4695- when using an objective limit, heuristic characters are not displayed any longer for worse solutions
4696
4697### Deleted and changed API methods
4698
4699- fixed spelling in the method name SCIPgmlWriteClosing()
4700
4701### New API functions
4702
4703- SCIPgetNLimSolsFound() to get number of solutions that respect the objective limit
4704
4705Fixed bugs
4706----------
4707
4708- fixed issue with applying the effective root depth during the search
4709- fixed bug concerning usage of dualbound and lowerbound
4710- fixed bug trying to color probing nodes, which are not added to the vbc output anymore
4711- fixed bug in sorting template
4712- fixed bug leading to removing a ranged row parallel to the objective function, although one of the sides was still needed
4713- fixed a bug correcting the binvarssorted flag in cons_linear.c
4714- fixed bug in cons_varbound.c not resolving multi-aggregated variables
4715- relaxed assert in SCIPvarCh{Lb,Ub}{Global,Local} that new bound must be tighter to feastol
4716- fixed contra-intuitive behavior when using SCIP with objective limits and solution limit at the same time;
4717 SCIP now only stops when sufficiently many solutions better than the objective limit have been found
4718- fixed bug when adding binary implications with non-vartype binary variables
4719- fixed bug adding binary implications on binary variables with type != `SCIP_VARTYPE_BINARY`
4720- fixed bug concerning different tolerances for reached objective limit in case of pricing with fastmip
4721
4722- LP:
4723 - fixed bug which disabled iteration limit in SCIPlpSolveAndEval()
4724 - ensure consistency of LP bounds during OBBT diving, i.e., that lower <= upper holds exactly
4725 - set lpsolstat to `SCIP_LPSOLSTAT_NOTSOLVED` in SCIPchg{Lp,Dual}feastol()
4726 - use tighter dual feasibility tolerance for LPs solved during optimization-based bound tightening
4727 - fixed bug with unflushed LP arising from global bound changes in strong branching
4728
4729- Constraints:
4730 - fixed issue with deleting varbound constraints in case the bound change was not applied
4731 - fixed bugs in parsing dis-/conjunctive constraints
4732 - fixed bug with handling of empty logicor and bounddisjunction constraints
4733 - fixed issue in cumulative constraint and separation
4734 - fixed bug when sorting knapsack constraints with the same weights
4735 - fixed bug resulting in trying to delete an upgraded linear constraint a second time in exitpre callback
4736 - fixed minor bug in conjunctive constraint handler printing wrong constraint
4737 - fixed bug in disjunctive constraint handler when enforcing a constraint
4738 - fixed behaviour change of indicator constraint handler when solving another instance after solving one using the
4739 interactive shell
4740 - fixed several issues in cumulative constraint handler
4741 - fixed bug in cumulative constraint handler w.r.t. getting active variables
4742 - fixed bug in cumulative constraint handler concerning conflict analysis
4743
4744- LPI and Interfaces:
4745 - fixed bug in CppAD in connection with abspower constraints
4746 - fixed bug in CppAD when using signpower functions with expression pointers that do not fit into an unsigned int
4747 - better handling of generalized (Lagrangian) variable bounds that are not in the LPI
4748 - fixed wrong basis rstat values in CPLEX LPI
4749 - fixed bug with LP not being flushed after bound changes on columns that are not in the LPI
4750 - methods SCIPlpiIs{PrimalFeasible,DualFeasible,DualUnbounded}() in SoPlex LPi now check that the LP is not perturbed,
4751 which may happen when stopping due to iteration or time limit
4752 - fixed inconsistencies between methods SCIPlpiIs{PrimalFeasible,DualFeasible,Optimal,...} in SoPlex LPi
4753
4754- Propagation:
4755 - fixed bug when adding linear constraints with non active variables in solving process, during propagation this
4756 resulted in changing the row, which is not possible for unmodifiable constraints/locked rows
4757 - fixed small issue in pseudo objective propagator w.r.t. propagating the lower bound globally
4758 - fixed bug in cons_orbitope: in rare cases one cannot repropagate
4759 - fixed bug of wrong result code in propagation in prop_genvbound.c
4760
4761- Presolve:
4762 - fixed bug in copying nonlinear constraints during presolve (resulted
4763 in wrongly declaring instances as infeasible when using component presolve)
4764 - fixed bug in copying nonlinear constraints during presolve (nonlinear part was not copied)
4765
4766- Heuristics:
4767 - fixed wrong solving status (OPTIMAL) in case an unbounded solution was provided or found by heuristic before presolve
4768 - fixed bug in heur_subnlp running with tightened tolerances: sumepsilon must be tightened like feastol and epsilon
4769 - fixed bug in nlp diving heuristic for fractional variables with values slightly outside of their domain
4770
4771- Numerics:
4772 - fixed several numeric issues
4773 - fixed numerical bug in conflict.c relaxing bounds while keeping an infeasibility proof
4774 - fixed feasibility decision bug when replacing inactive variables by their active counterparts, which might change the
4775 redundancy status of a bounddisjunction constraint due to numerics
4776 - fixed numerical bug adding a relaxed bound for conflict analysis in cons_varbound
4777 - fixed numerical bug in conflict analysis of genvbounds propagator
4778
4779@section RN300 SCIP 3.0.0
4780*************************
4781
4782Features
4783--------
4784
4785- SCIPcomputeLPRelIntPoint() with normtype=`s` now uses homogenized LP for computing rel.int. point too and allow to
4786 set relaxrows = FALSE
4787- new column showing the pseudo objective value
4788- digraph structure added to misc.c and pub_misc.h that can be used to handle directed graphs, compute undirected
4789 components in the graph and sort these components (almost) topologically
4790- SCIP does now print an info message when the root LP could not be solved or is unbounded
4791- added counter and clock for SCIPcopy() calls
4792- correct initialization of steepest edge weights with SoPlex 1.6.0.4
4793- parameters can now be fixed, which means that their value cannot be changed unless they are unfixed, first;
4794 the fixing status of a parameter is copied to sub-SCIPs, which allows to ensure that certain parameters
4795 are also not changed when, e.g., heuristics change emphasis settings or also specific parameters
4796- automatic transfer of original solutions (e.g., provided by the user, from solution pool, after restart, from heuristic
4797 adding original solution during solve) to the transformed space (might fail due to, e.g., dual fixings)
4798- added possibility to use GUBs for lifting knapsack cuts (disabled)
4799- added pre- and post-conditions in doxygen documentation for all methods of scip.{c,h}
4800- added zeroobj heuristic that solves a copy of the problem without an objective function and with quite strict limits
4801 on the number of nodes and LP iterations
4802- complete reworking of the vbounds propagator: it now takes into account variable bounds, cliques and implications,
4803 stores bounds of variables which were changed and performs a forward propagation from these bounds, i.e., tries to
4804 derive new bounds for other variables; during propagation, bound changes are propagated in an (almost) topological order
4805
4806- Constraints:
4807 - full version of cumulative constraint handler
4808 - new constraint handler `superindicator` for indicator constraints with slack constraints of arbitrary type
4809 - implemented first clique lifting procedure in cons_setppc.c (by default is off)
4810 - the conjunction and disjunction constraint handlers are now able to parse their CIP output format
4811
4812- Memory:
4813 - better handling of memory limits, in particular for large problems
4814 - estimate memory consumption for sub-SCIP and do not copy them if close to memory limit
4815
4816- Presolve:
4817 - time for initpre and exitpre methods is now also measured in presolving time
4818 - added dual presolving for and-constraints difficult instances (no guarantees)
4819 - oneopt can now be called before presolving
4820 - added a presolving step in the disjunctive constraint handler, removing disjunction, where a sub-constraint was
4821 deleted, which means this sub-constraint is redundant, which again means it is always TRUE or will be enforced by
4822 another constraint
4823 - added new presolver convertinttobin, which converts bounded integer variables to their binary representation, e.g.
4824 for integer variable 0 <= x <= 10 the binary variables y0, y1, y2 and y3 are created, such that
4825 1 y0 + 2 y1 + 4 y2 + 8 y3 <= 10 and x = 1 y0 + 2 y1 + 4 y2 + 8 y3
4826 - added new presolver gateextraction, which tries to find and-gates/constraints which are linearized
4827 e.g. (x + y + z >= 1, x + y <= 1 and x + z <= 1 => x == AND(~y,~z)), in special cases it also detects set-partitioning
4828 constraints e.g. (x + y + z >= 1, x + y <= 1, x + z <= 1 and y + z <= 1 => x + y + z == 1));
4829 gate-extractor is also able to detect logicor constraints and set-packing/-partitioning constraints with the same
4830 variables, to upgrade these both constraints to a set-partitioning constraint
4831 - added new presolver components, that searches for independent components in the problem structure and solves
4832 these components as sub-SCIPs when they are small enough (per default <= 20 discrete variables, nodelimit of 10000)
4833 - added new presolver domcol that looks for dominated columns in a MIP and tries to fix them
4834
4835- Reader:
4836 - CNF reader now creates feasibility instances per default, usage of an objective has to be set by a parameter
4837 - added reader for MI(NL)Ps in OSiL (Optimization Services Instance Language) format
4838
4839- Statistic:
4840 - new statistics and new statistic output messages
4841 - number of presolving calls of plugins is counted and displayed in the statistics,
4842 can be accessed via SCIPpresolGetNCalls() and SCIP{prop/conshdlr}getNPresolCalls()
4843 - the statistics shows for a branching rule the number of calls for LP, extern and pseudo candidates
4844 - new switch `SCIP_STATISTIC` and new macros SCIPstatisticMessage(), SCIPstatisticPrintf() and SCIPstatistic() to output
4845 statistic and execute code lines which are only needed therefor. Works as `SCIP_DEBUG` and SCIPdebugXyz()
4846 - added statistics on the number of cuts/rows that have actually been applied to the lp for each constraint handler and separator;
4847 use SCIPcreate(Empty)RowCons() and SCIPcreate(Empty)RowSepa() to support the statistics.
4848
4849- NLP:
4850 - new propagators obbt and genvbounds for MINLP
4851 - new NLPI parameter `SCIP_NLPPAR_FASTFAIL` to enable convergence checks in NLP solver to stop early on seemingly
4852 - added nlpdiving heuristic that comprises several diving heuristics using an NLP relaxation
4853
4854Performance improvements
4855------------------------
4856
4857- improved scaling by choosing the smallest scaler
4858- if first root lp is solved and the optimality is rejected by SCIP, there won't be an unnecessary solving of the lp
4859 from scratch again
4860- several performance improvements for Pseudo-Boolean optimization, pseudo objective propagator
4861- streamlined initlp functions in cons_indicator, cons_sos1, cons_sos2 (add rows only if needed)
4862- improved time used for adding implications
4863- speed up in SCIPboolarrayExtend() in misc.c replacing a for loop with BMSmoveMemoryArray() call
4864- speed up in var.c changing some recursive calls into iterative calls and reducing the number of VARFIX event that are
4865 thrown for fixation, aggregation or multi-aggregations
4866- revised reduced cost propagator
4867- increased performance in SCIPcliqueAddVar(), adding a variable to a clique
4868- tighten primal and dual feasibility tolerances independently if they are not reached in LP solving
4869
4870- Probing:
4871 - if probing reached the end of all variables it will restart the probing cycle correctly
4872 - improved probing by ordering the variables differently and applying the one-branch before the zero-branch
4873
4874- Constraints:
4875 - improved scaling of linear constraints, linear constraints with integral variables will now be scale with
4876 1e+06/MAX(maximal absolute coefficient, 1.0) instead of 1e+03/MAX(maximal absolute coefficient, 1.0);
4877 if all coefficients are in absolute value equal they will be scaled by that
4878 - added clique presolving for and-constraints, which checks if two operands or one operand and the resultant are in a
4879 clique and then fixes the resultant to 0 and in the former case we can delete the and-constraint too
4880 - speed up in linear constraint handler replacing aggregated variables
4881 - when all nonlinearities have been fixed and the number of nonfixed variables is 1 in cons_nonlinear/cons_quadratic/
4882 cons_bivariate, handle it by a bound change instead of adding a linear constraint
4883
4884- Separation:
4885 - automatically turn off separation in sepa_oddcycle if it was too unsuccessful within the last calls
4886 - use faster Dijkstra variants in sepa_oddcycle
4887 - improved tcliquegraphAddImplicsVars() in sepa_clique.c to faster add possible variables
4888 - changed emphasis settings: knapsack disaggregation is now allowed in fast presolving, CG-MIP separator disabled in
4889 aggressive separation
4890
4891- Reader:
4892 - improved lp-, mps-, opb-reading time
4893 - speed up mps reader asking parameters only once
4894
4895- Heuristics:
4896 - added parameters mincoveredrel and mincoveredabs to heur_undercover to only run if problem is sufficiently nonlinear
4897 - improved intdiving heuristic by activating backtracking to a different fixing value
4898 - heur_undercover treats indicator constraints as nonlinear and fixes the binary variable for linearization
4899
4900Examples and applications
4901-------------------------
4902
4903- new examples for scheduling and usage of the callable library with nonlinear problems
4904- the error messages are not handled via the message handler anymore; per default the error message a written to stderr
4905
4906Interface changes
4907-----------------
4908
4909- introduced basic inclusion and creation methods to simplify usage of the SCIP library
4910- allowed to start diving mode even if LP is not flushed, not solved, or not solved to optimality
4911- changed the message handler system within SCIP heavily such that it is thread save
4912- the resolve propagation methods for the constraint handler and propagator getting a new parameter called relaxedbd;
4913 explaining/resolving this relaxed bound is sufficient
4914- default integer comparer SCIPsortCompInt() (see pub_misc.h)
4915
4916- LP interface:
4917 - SoPlex LPI supports setting of `SCIP_LPPAR_DUALFEASTOL` when using SoPlex version 1.6.0.5 and higher.
4918
4919- Problem:
4920 - Forbid problem modifications in `SCIP_STAGE_{INIT,EXIT}PRESOLVE` (see pre-conditions for corresponding methods in scip.h).
4921
4922- Miscellaneous:
4923 - New macro SCIPdebugPrintCons() to print constraint only if `SCIP_DEBUG` flag is set.
4924 - all objscip *.h file now use the default SCIP interface macros (this should avoid errors when changing the interface)
4925
4926### New and changed callbacks
4927
4928- Constraint Handler:
4929 - Added a propagation timing parameter `proptiming` to SCIP_DECL_CONSPROP(), giving the current timing at which
4930 this method is called (also to the corresponding c++ wrapper classes).
4931 - New optional callback methods in constraint handlers: `SCIP_DECL_CONSGETVARS` and `SCIP_DECL_CONSGETNVARS`.
4932 These callbacks, if implemented, should return an array of all variables and the number of all variables used
4933 by the given constraint, respectively. (This method might, e.g., be called by a presolver)
4934
4935- NLP Solver Interface:
4936 - New NLPI callback SCIP_DECL_NLPISETMESSAGEHDLR() to set message handler in NLP solver interfaces.
4937
4938- Propagator:
4939 - Added a propagation timing parameter `proptiming` to SCIP_DECL_PROPEXEC(), giving the current timing at which this method is
4940 called (also to the corresponding c++ wrapper classes).
4941
4942- Plugin management:
4943 - added `basic` inclusion methods which have only fundamental data of the plug-ins as arguments; added setter functions
4944 for all non-fundamental callbacks of the plug-ins; the plug-in types with basic inclusion functions are:
4945 readers, constraint handlers, conflict handlers, presolvers, propagators, heuristics, separators, relaxation handlers,
4946 branching rules, node selectors and pricers; these methods should make the usage easier, sparing out optional callbacks and
4947 parameters: e.g., SCIPincludeConshdlrBasic();
4948 - To extend the basic functionalities, there are setter method to add
4949 optional callbacks. For example SCIPsetConshdlrParse(), SCIPsetPropCopy() or SCIPsetHeurInitsol().
4950
4951- Constraint Handlers:
4952 - Added basic creation methods for all constraints types, e.g., SCIPcreateConsBasicLinear(); these methods should make the usage easier,
4953 sparing out optional callbacks and parameters.
4954
4955### Deleted and changed API methods
4956
4957- SCIPcomputeCoverUndercover() now has an additional parameter coverbd
4958- tcliqueMaxClique has an additional parameter to store the number of used branch-and-bound nodes
4959- the code in `src/dijkstra` and `src/xml` has been changed to (increasingly) conform to the SCIP coding style;
4960 all function (and variable) names have been changed (do not contain `_` anymore).
4961- renamed SCIPstairmap*Core() to SCIPstairmap*Stair()
4962
4963- Conflict Analysis:
4964 - Added parameter `relaxedbds` to conflict handler callback method SCIP_DECL_CONFLICTEXEC(). This array contains
4965 bounds which are sufficient to create a valid conflict
4966
4967- Constraint Handler:
4968 - Added a parameter `restart` to the SCIP_DECL_CONSEXITSOL() callback method, indicating whether this call was
4969 triggered by a restart.
4970 - Added a parameter `relaxedbd` to SCIP_DECL_CONSRESPROP() callback method. If explaining a given bound change
4971 (index), it is sufficient to explain the reason for reaching the `relaxedbd` value, see above
4972 - Removed parameters `isunbounded`, `isinfeasible` and `result` from SCIP_DECL_CONSINITPRE() and SCIP_DECL_CONSEXITPRE()
4973 callback methods. It is not allowed to determine unboundedness or infeasibility in these callbacks, anymore.
4974 - added a `SCIP_CONS*` parameter to SCIPcreateConsDisjunction() which can represent the linear relaxation of the whole
4975 disjunction constraint as a conjunction constraint, or `NULL`
4976 - remove problematic function cons_indicator:SCIPsetSlackVarIndicator()
4977 - Renamed SCIPgetCountedSparseSolutions() to SCIPgetCountedSparseSols() in cons_countsols.{c,h}.
4978
4979- Counting:
4980 - Changed the counting system within SCIP heavily. New method for `SCIP_SPARSESOL` usage, SCIPsparseSolCreate(),
4981 SCIPsparseSolFree(), SCIPsparseSolGetVars(), SCIPsparseSolGetNVars(), SCIPsparseSolGetLbs(), SCIPsparseSolGetUbs()
4982 in (pub_)misc.{c,h}.
4983
4984- Cuts and Separation:
4985 - removed `targetscip` parameter from SCIPconvertCutsToConss(), now this function can only convert cuts on one instance,
4986 otherwise use SCIPcopyCuts()
4987 - added `ncutsadded` parameter to SCIPcopyCuts() to be able to store the number of copied/converted cuts
4988 - New functions SCIPcreateEmptyRowCons(), SCIPcreateEmptyRowSepa(), SCIPcreateRowCons(), and SCIPcreateRowSepa() that allow
4989 to set the originating constraint handler or separator of a row respectively; this is, for instance, needed for statistics
4990 on the number of applied cuts. If rows are created outside a constraint handler or separator use SCIPcreateRowUnspec() and
4991 SCIPcreateEmptyRowUnspec(). The use of SCIPcreateEmptyRow() and SCIPcreateRow() is deprecated.
4992 - New functions SCIProwGetOrigintype(), SCIProwGetOriginCons(), and SCIProwGetOriginSepa() to obtain the originator
4993 that created a row.
4994
4995- LP:
4996 - new parameter numerics/lpfeastol for primal feasibility tolerance used in LP solver
4997 - SCIPcomputeLPRelIntPoint() takes two new arguments giving a time and iteration limit
4998 - SCIPcolGetStrongbranchLPAge(), SCIPgetVarStrongbranchLPAge(), SCIPgetNLPs(), SCIPgetNPrimalLPs(), SCIPgetNDualLPs(),
4999 SCIPgetNBarrierLPs(), SCIPgetNResolveLPs(), SCIPgetNPrimalResolveLPs(), SCIPgetNDualResolveLPs(), SCIPgetNNodeLPs(),
5000 SCIPgetNNodeInitLPs(), SCIPgetNDivingLPs(), SCIPgetNStrongbranchs(), SCIPgetNRootStrongbranchs() now return a longint
5001 instead of an integer
5002
5003- Message Handler and Printing:
5004 - New callback method SCIP_DECL_MESSAGEHDLRFREE() which is called when the message handler is freed.
5005 - The old callback method SCIP_DECL_MESSAGEERROR() was replaced by the callback method SCIP_DECL_ERRORPRINTING().
5006 - the follwing methods additionally need the SCIP pointer as parameter to make the output thread save:
5007 SCIPprintVersion(), SCIPsetMessagehdlr(), SCIPgetMessagehdlr() and SCIPwarningMessage()
5008 - the error printing method can be replaced using the method SCIPmessageSetErrorPrinting(); the default error message
5009 printing can be recoverd via SCIPmessageSetErrorPrintingDefault() (see pub_message.h)
5010 - Changed the message handler system within SCIP heavily such that it is thread-safe. SCIPcreateMessagehdlr() in
5011 scip.{c,h} was replaced by SCIPmessagehdlrCreate() in pub_message.h/message.c with a changed parameter list;
5012 see pub_message.h and type_message.h.
5013 - removed method SCIPcreateMesshdlr(), please use SCIPmessagehdlrCreate() (see pub_message.c)
5014 - removed method SCIPfreeMesshdlr(), please use SCIPmessagehdlrRelease() (see pub_message.c)
5015 - Error messages (SCIPerrorMessage()) are not handled via the message handler anymore; per default the error
5016 message is written to stderr.
5017 - the following methods need an additional message handler: SCIPdispLongint(), SCIPdispInt(), SCIPdispTime(), all message
5018 handler methods (see pub_message.h), SCIPhashtablePrintStatistics(), SCIPhashmapPrintStatistics(), SCIPlpiCreate()
5019 - SCIPprintCons() does not print termination symbol `;\n` anymore; if wanted, use SCIPinfoMessage() to print `;\n` manually
5020 - remove SCIPcolPrint() and SCIProwPrint(), please use SCIPprintCol() SCIPprintRow() see scip.h
5021 - method SCIPprintError() does not need the file stream anymore. The error is written via the error message callback.
5022
5023- Nonlinear expressions, relaxation, and solver interface:
5024 - Method SCIPexprtreeRemoveFixedVars() is not public anymore.
5025 - Renamed SCIPmarkNonlinearitiesPresent() to SCIPenableNLP()
5026 - Renamed SCIPhasNonlinearitiesPresent() to SCIPisNLPEnabled().
5027 - removed SCIPmarkContinuousNonlinearitiesPresent(),
5028 renamed SCIPhasContinuousNonlinearitiesPresent() to SCIPhasNLPContinuousNonlinearity() and allow call only during
5029 initsolve and solve,
5030
5031- Parameters:
5032 - Replaced SCIPparamSet*() by SCIPchg*Param()
5033 + replaced SCIPparamSetBool() by SCIPchgBoolParam()
5034 + replaced SCIPparamSetInt() by SCIPchgIntParam()
5035 + replaced SCIPparamSetLongint() by SCIPchgLongintParam()
5036 + replaced SCIPparamSetReal() by SCIPchgRealParam()
5037 + replaced SCIPparamSetChar() by SCIPchgCharParam()
5038 + replaced SCIPparamSetString() by SCIPchgStringParam()
5039
5040- Presolving:
5041 - Removed parameters `isunbounded`, `isinfeasible` and `result` from SCIP_DECL_PRESOLINITPRE() and
5042 SCIP_DECL_PRESOLSEXITPRE(). It is not allowed to determine unboundedness or infeasibility in these callbacks, anymore.
5043
5044- Propagator:
5045 - changed parameters of function SCIPpropagateCutoffboundVar() in prop_pseudoobj.{c,h}
5046 - Added a parameter `restart` to SCIP_DECL_PROPEXITSOL() callback method, indicating whether this call was triggered
5047 by a restart.
5048 - Added a parameter `relaxedbd` to SCIP_DECL_PROPRESPROP() callback method. If explaining a given bound change
5049 (index), it is sufficient to explain the reason for reaching the `relaxedbd` value.
5050 - Removed parameters `isunbounded`, `isinfeasible` and `result` from SCIP_DECL_PROPINITPRE() and
5051 SCIP_DECL_PROPEXITPRE() callback methods. It is not allowed to determined unboundedness or infeasibility in
5052 these callbacks, anymore.
5053
5054- Sort and Copy:
5055 - The methods SCIPsortedvecInsert*() have an additional parameter which can be used to receive the position where
5056 the new element was inserted, if this is not of interest a `NULL` pointer can be given
5057 - new parameter in SCIPcopyPlugins() to indicate whether the message handler from the source SCIP should be passed to the
5058 target SCIP (only the pointer is copied and the usage counter of the message handler is increased)
5059 - New parameter in SCIPcopy() to indicate whether the message handler from the source SCIP
5060 should be passed to the target SCIP (only the pointer is copied and the usage counter of the message handler is
5061 increased). In multi theaded enviroment this parameter needs to be set to FALSE.
5062
5063- Variable usage:
5064 - rename SCIPvarGetBestBound() to SCIPvarGetBestBoundLocal()
5065 - rename SCIPvarGetWorstBound() to SCIPvarGetWorstBoundLocal()
5066 - Method SCIPvarGetProbvarSum() is not public anymore, use SCIPgetProbvarSum() instead.
5067 - Replaced method SCIPvarGetRootRedcost() by SCIPvarGetBestRootRedcost().
5068
5069### New API functions
5070
5071- setup timer to all plugins and therefore SCIP<plugin-type>GetSetupTime() methods in all pub_plugin-type.h to ask
5072 for this time (, e.g. SCIPeventhdlrGetSetupTime() in pub_event.h)
5073- new GML(Graph Modeling Language) methods SCIPgmlWriteOpening(), SCIPgmlWriteCosing(), SCIPgmlWriteArc(), SCIPgmlWriteEdge(),
5074 SCIPgmlWriteNode() that write to a given GML file
5075- new LPI method SCIPlpiGetObjsen() to query objective sense
5076- SCIPpermuteIntArray() in pub_misc.h and misc.c for permuting an integer array
5077- SCIPcalcBinomCoef() in pub_misc.h and misc.c which calculates a binomial coefficient up to 33 over 16
5078- SCIPheurPassSolAddSol() in heur_trysol.c; solution which are passed via this method are just without any feasibility check
5079- SCIPgetGlobalPseudoObjval() which returns the global pseudo objective value which is all variables
5080 set to their best (w.r.t. the objective function) global bound
5081- SCIPhashGetKeyStandard() which returns the element itself as the key, SCIPhashKeyEqPtr(),
5082 SCIPhashKeyValPtr() which do the hash-comparison/-conversion on a pointer in pub_misc.h
5083- SCIPhashtableClear() which removes all elements of a hash table
5084- SCIPisUpdateUnreliable() to check whether an iteratively updated value should be recomputed from scratch
5085 (e.g., for activities; uses new parameter `misc/num_recompfac`)
5086- SCIPisHugeValue() to check whether a value is huge and should be handled separately from other values
5087 (e.g., in activity computations) and SCIPgetHugeValue() to get the smallest value counting as huge
5088- SCIPfixParam() and SCIPunfixParam() to fix and unfix a parameter, respectively;
5089 the fixing status of a parameter can be requested by SCIPparamIsFixed();
5090- SCIPsetBasePointClosecuts() to set the base point for close cut separation
5091- SCIPchgCutoffboundDive() to change the cutoffbound in diving mode
5092- SCIPupdateCutoffbound() which can be used to pass a cutoff bound
5093
5094- Presolving:
5095 - SCIPpropIsPresolDelayed() which return if a propagator is delay during presolving
5096 - Added method SCIPisPresolveFinished() which returns whether the presolving process would be stopped after the
5097 current presolving round, given no further reductions will be found, can be used to ensure that a presolver is called very late
5098
5099- Memory:
5100 - added forgotten implementation of SCIPfreeMemorySize(), SCIPfreeMemorySizeNull() in scip.h and BMSfreeMemorySize(),
5101 BMSfreeMemorySizeNull() in memory.h
5102 - SCIPmemccpy() in pub_misc.h and misc.c which copies either a specified number of charcters of a source
5103 string to a destination string or until it hits a stoping character
5104 - BMSmoveMemory(), BMSmoveMemoryArray(), BMSmoveMemorySize() and corresponding BMSmoveMemory_call() in
5105 memory.{h,c} too move memory elements
5106
5107- Conflict Analysis:
5108 - SCIPisConflictAnalysisApplicable() which return FALSE is the conflict will not runs; can be used
5109 to avoid unnecessary initialization of the conflict analysis
5110 - SCIPaddConflictRelaxedLb(), SCIPaddConflictRelaxedUb() and SCIPaddConflictRelaxedBd(); these methods
5111 can be used to give for a bound change which is part of an explanation a relaxed bound; this means the relaxed bound
5112 is already efficient to be part of a valid explanation
5113 - SCIPisConflictVarUsed() returns TRUE if the given bound change is already part of the conflict set;
5114 that is the bound change is redundant;
5115 - SCIPgetConflictVarLb() and SCIPgetConflictVarUb() returning the lower/upper bound of the given
5116 variable within the current active conflict set
5117
5118- Variable usage:
5119 - SCIPvarsGetProbvar() in pub_var.h and var.c, which returns for a given array of variables the active, fixed
5120 or multiaggregated representation
5121 - SCIPgetActiveVars() in scip.{h,c}, which returns for a given array of variables the active counterparts
5122 - SCIPgetNObjVars() which returns the number of variables which have a non-zero objective coefficient
5123 - SCIPenableVarHistory() and SCIPdisableVarHistory() which can be used to turn off and on the collection
5124 of variables statistics which is used for example for branching
5125 - SCIPbranchVarHole() which branches a variable w.r.t. a given domain hole
5126 - SCIPvarGetAggregatedObj() which computes for a (not active) variable the corresponding objective value
5127 - SCIPsolIsOriginal() that returns whether a solution is defined on the original variables
5128 - SCIPgetVarImplRedcost() which returns the implied reduced costs
5129 - SCIPvarGetBestRootSol(), SCIPvarGetBestRootRedcost(), SCIPvarGetBestRootLPObjval() which return the best
5130 combination for a variable w.r.t. root solution value, root LP objective value and root reduced cost
5131 - SCIPhaveVarsCommonClique() in scip.{h,c}, to check for common clique information on two given variables
5132 - added basic creation methods SCIPcreateVarBasic() and SCIPcreateProbBasic() and setter functions for
5133 non-fundamental callbacks of variables and problems.
5134 - added new methods SCIPvarGetBestBoundGlobal() and SCIPvarGetWorstBoundGlobal().
5135
5136- Constraint Handler:
5137 - added public wrapper functions for calling constraint handler callback methods for a single constraint:
5138 SCIPactiveCons(), SCIPdeactiveCons(), SCIPinitlpCons(), SCIPsepalpCons(), SCIPsepasolCons(), SCIPpropCons(),
5139 SCIPrespropCons(), SCIPenfopsCons(), SCIPenfolpCons()
5140 - added basic creation methods for all constraint handlers
5141 - SCIPchgCapacityKnapsack() which can be used to change the capacity of a knapsack constraint
5142 - SCIPconsIsAdded() which returns whether a constraint was already to a SCIP instance
5143 - SCIPconshdlrGetNCutsApplied() in pub_cons.h to get the number of cuts applied to the lp
5144 - SCIPconshdlrIncNAppliedCuts() in cons.h to increase the number of applied cuts (used by sepastore.c)
5145 - SCIPchgVarName() and SCIPchgConsName() which can be used to change name of variables and
5146 constraints in problem creation stage
5147 - New methods SCIPgetConsVars() and SCIPgetConsNVars() which return for a given constraint the involved variables and
5148 the number of variables if the corresponding constraint supports this (optional) callbacks
5149 (corresponding callbacks need to be implemented, see above)
5150
5151- Message Handler:
5152 - SCIPmessagehdlrCapture() which captures a given message handler (increases number of uses)
5153 - SCIPmessagehdlrRelease() which releases and possibly frees a given message handler (decreases number of uses)
5154 - SCIPsetMessagehdlrLogfile() which can be used to write into a log file
5155 - SCIPsetMessagehdlrQuiet() which can be used to turn the screen output on and off
5156
5157### Command line interface
5158
5159- in the interactive shell, parameters can be fixed and unfixed with `fix` (instead of `set`), e.g., `fix heuristics rens freq TRUE`;
5160- new shell command `change minuc` to minimize the number of unsatisfied constraints
5161
5162### Interfaces to external software
5163
5164- beta-version of a MATLAB interface can be found under interfaces/matlab
5165- beta-version of a AMPL interface can be found under interfaces/ampl
5166
5167### Changed parameters
5168
5169- `branching/fullstrong/reevalage` changed from an integer to a longint parameter
5170
5171- Removed parameters:
5172 - `separating/closecuts/separootonly`
5173 - `constraints/quadratic/defaultbound`
5174 - `separating/cgmip/nodelimit`
5175
5176### New parameters
5177
5178- `constraints/%s/timingmask` for changing the timingmask for calling the propagtion method of all constraint plugins
5179- `constraints/and/dualpresolving` by default set to TRUE, enabling dual-presolving on and-constraints
5180- `constraints/indicator/{sepacouplingcuts,sepacouplinglocal}` to enable separation of (local) cuts
5181- `constraints/indicator/{maxsepacuts,maxsepacutsroot}` to restrict the number of separated cuts
5182- `constraints/indicator/dualreductions` to enable dual presolving/propagation steps
5183- `constraints/setppc/cliquelifting`, `constraints/setppc/addvariablesascliques`,
5184 `constraints/setppc/cliqueshrinking`, first for enabling/disabling the clique lifting algorithm in cons_setppc.c,
5185 second parameter is for trying to create extra clique constraints in lifting algorithm, third parameter is for trying
5186 to decrease the number of variable in a clique constraint in the lifting algorithm
5187- `limits/totalnodes` that allows to stop at the correct node if a restart occured; therefore the new
5188 `SCIP_STATUS_TOTALNODELIMIT` is added
5189- `lp/{rootiterlim,iterlim}` to set a limit on the LP iterations spend in the initial root LP and each
5190 LP resolve, respectively
5191- `misc/transorigsols` by default set to TRUE, that switches whether SCIP tries to transfer original
5192 solutions into the transformed space (in initsol and if a heuristic adds an original solution during solving)
5193- `numerics/hugeval` that defines the smalles value counting as huge (see new method SCIPisHugeValue())
5194- `numerics/recompfac` which denotes the factor, by which the absolute of an iteratively updated value has
5195 to be decreased in order to recompute the value from scratch
5196- `presolving/convertinttobin/maxdomainsize` by default is set to `SCIP_LONGINT_MAX`, which deternmines
5197 the domainsize for which integers are converted to their binary representation
5198- `presolving/convertinttobin/onlypoweroftwo` by default is set to FALSE, that parameter allows you to
5199 only convert integer variables with a domainsize of 2^p-1 to their binary representation
5200- `presolving/convertinttobin/samelocksinbothdirections` by default is set to FALSE, that parameter allows
5201 you to convert only integer variables to their binary representation, which have the same amount of up- and downlocks
5202- `presolving/gateextraction/sorting` by default is set to 1, that parameter determines if you want to try
5203 to extract big-gates(-1) or small-gates(1) at first by ordering bigger/smaller logicor constraint up front, or use
5204 them as they are (0)
5205- `presolving/gateextraction/onlysetpart` by default is set to FALSE, that parameter allows you to
5206 only extract set-partitioning and no and-constraints
5207- `presolving/gateextraction/searchequations` by default is set to TRUE, that parameter allows you to
5208 search for logicor constraints and set-packing/-partitioning constraints with same variables
5209- `propagating/%s/timingmask` for changing the timingmask for calling the propagtion method of all propagator plugins
5210- `propagating/probing/maxdepth` to set the maximal depth until the probing propagation is executed
5211- `reading/cnfreader/useobj` to state whether an artificial objective, depending on the number of clauses
5212 a variable appears in, should be used, by default set to FALSE, old default behavior of reader corresponds to TRUE
5213- `separating/cgmip/{minnodelimit,maxnodelimit}` to determine node limit.
5214- `separating/closecuts/maxlpiterfactor` for iteration limit in relative interior point computation
5215- `separating/oddcycle/maxunsucessfull` to automatically turn off separation
5216- `oncepernode` in Rounding and Simple Rounding heuristic
5217
5218### Data structures
5219
5220- new data structure for binary trees (`SCIP_BT` and `SCIP_BTNODE` in pub_misc.h)
5221- renamed data structure `SCIP_STAIRMAP` to `SCIP_PROFILE`
5222- added new stages `SCIP_STAGE_INITPRESOLVE`, `SCIP_STAGE_EXITPRESOLVE` and `SCIP_STAGE_FREE`; renamed `SCIP_STAGE_FREESOLVE`
5223 to `SCIP_STAGE_EXITSOLVE`
5224- Changed the counting system within SCIP heavily. `SPARSESOLUTION` was renamed to `SCIP_SPARSESOL` and moved
5225 from cons_countsols.h to struct_misc.h
5226
5227Testing
5228-------
5229
5230- the check script now recognizes MIQCP and MINLP instances
5231- make test now also checks instances in wbo, cnf, osil and fzn format
5232- renamed parameter SCRDIR of `make testgams` to CLIENTTMPDIR and changed its default to `/tmp`
5233
5234Build system
5235------------
5236
5237### Makefile
5238
5239- CppAD source code is now distributed with SCIP (`src/cppad`), so that `lib/cppad` is not used anymore;
5240 the default for EXPRINT has changed from none to cppad
5241
5242Fixed bugs
5243----------
5244
5245- fixed bug with strong branching with the LP status for conflict analysis
5246- fixed bug w.r.t. adding a value to the objective offset of the transformed problem
5247- fixed wrong assert in feasibility pump stage 3
5248- fixed bug in solve.c, applied bounding for the initial lp was only done if root-lp-solution was valid but another
5249 solution could also have been added
5250- primal solutions with infinite objective value are now automatically discarded
5251- all plugins that solve sub-SCIPs now do not stop the whole solution process if there has been an error
5252- fixed bug in cip reader, wrong use of SCIPstrtok()
5253
5254- Variables:
5255 - fixed bug in shiftandpropagate w.r.t. SCIPconstructLP() which can have the side effect that variables are created
5256 - method SCIPvarGetProbvarSum() (and thus also SCIPgetProbvarSum()) returns +/-infinity if the variable resolves to a
5257 variable fixed to +/-infinity (depending on the sign of the scalar) but does not multiply with the scalar, anymore
5258 - better handling of infinite solution values for aggregated and negated variables
5259 - fixed bug that disabled multi-aggregation of two integer or implicit integer variables
5260 - fixed bug in sol.c with requesting values of transformed variables in original solution; previously this had only
5261 been handled in SCIPgetSolVal(), now the handling has been moved to SCIPsolGetVal()
5262 - fixed several bugs writing an mps file in the reader_mps.c, e.g. writing fixed variables which are not (yet) removed
5263 and writing integer variables even with an objective value of 0, if they only exist in non-linear constraints
5264
5265- Separation:
5266 - fixed minor bugs with respect to counting generated and lifted cuts in sepa_oddcycle
5267 - fixed bug in sepa_clique.c, could not handle only empty cliques, that were not removed
5268
5269- Heuristics:
5270 - fixed potential bugs in shiftandpropagate heuristic concerning the transformation update of a variable with free status
5271 - fixed bug in heur_zirounding with computation of up/downslacks
5272 - fixed bug in mutation heuristic with unnecessary aborts due to a wrong memory limit
5273 - fixed potential bug in fix-and-infer heuristic with variables being fixed to infinite value
5274 - fixed bug in diving heuristics with variables being fixed to values outside their domain
5275 - fixed bug in simple rounding heuristic with column generation for variables with strictly positive lower bound
5276 - made Octane heuristic numerically more stable to avoid asserts being caused by cancellation
5277 - fixed bug in mutation heuristic with variables being fixed to infinite values
5278 - do not run heur_shiftandpropagate if there is no LP
5279
5280- LP Interface:
5281 - fixed bug in Cplex LPI: after running simplex, solisbasic flag was always true, which might be wrong if Cplex hit a
5282 time limit
5283 - fixed bug in SCIP probing mode with cleared LPI state but solved LP
5284 - fixed assert with `LPI=none` (need to count rows/cols in lpi_none)
5285 - fixed bug in SoPlex LPI where objective sense was not correct after reading LP from file in SCIPlpiReadLP()
5286
5287- Constraints:
5288 - fixed bug in scip.c adding a constraint in SCIPgetConsCopy() to the constraint hashmap
5289 - fixed bug in cons_linear w.r.t recalculation of unreliable activities
5290 - fixed bug in cons_linear concerning huge activity values: besides infinite contributions, we now also treat huge
5291 contributions separately, count their occurences in a constraint and provide a relaxed activity value
5292 - fixed bug in cons_xor.c parsing a constraint
5293 - fixed count of propagations in cons_indicator and only try to propagate if variables are not yet fixed
5294 - fixed some bugs in cons_disjunction.c (wrong assert, forgotten deletion of constraint, wrong SCIPreleaseCons() call)
5295
5296Miscellaneous
5297-------------
5298
5299- first release of GCG, a generic branch-cut-and-price solver built on top of SCIP
5300- first release of UG, a framework for solving mixed integer programs, mixed integer
5301 nonlinear programs and constraint integer programs in parallel
5302- new SCIP T-shirts
5303- renamed ZIB Optimization Suite to SCIP Optimization Suite
5304
5305@page RN21 Release notes for SCIP 2.1
5306
5307@section RN212 SCIP 2.1.2
5308*************************
5309
5310Performance improvements
5311------------------------
5312
5313- fixed performance issue in debug mode, where SCIPvarGetLPSol_rec() calculated a value to often, which in the end lead
5314 to exponential growth in running time
5315- force cuts from linearizations of convex constraint in NLP relax solution into LP, thus allowing faster proving of
5316 optimality for convex NLPs
5317
5318Fixed bugs
5319----------
5320
5321- fixed bug in varAddTransitiveImplic() in var.c, when adding implications on special aggregated, namely negated, variables
5322- fixed issue if a primal solution leads to a cutoff of the current focus node
5323- fix compilation issues with zlib 1.2.6
5324- fixed bug in SCIPsolveKnapsackExactly(), trying to allocate too much memory which led to an overflow and later to a segmentation fault
5325- fixed bug in sepa_rapidlearning, carrying on the optimization process, when already solved
5326
5327- Heuristics:
5328 - fixed bug in heur_undercover.c, where a variable with fixed bounds but not of status `SCIP_VARSTATUS_FIXED` was wrongly handled
5329 - fixed bug in heur_oneopt.c which forgot to check LP rows if local rows are present
5330
5331- Constraints:
5332 - fixed bug in SCIPsolveKnapsackExactly()
5333 - fixed bug in cons_quadratic where bounds on activity of quadratic term were not always invalidated when quadratic variables were removed
5334 - fixed bug in cons.c, where after a restart the arrays for all initial constraints were corrected in the initsol process
5335 instead of the initpre process, this was to late because you might change the status in presolving which lead to an assert()
5336 - fixed bug in NLP representation of abspower constraints handling (x+a)^2 with nonzero a
5337 - fixed bug parsing an and-constraint in cip format
5338 - fixed bug in cons_setppc, did not handle new constraints with inactive variables
5339 - fixed bug in cons_xor.c which did not copy the artificial integer variable (used for the lp relaxation)
5340
5341@section RN211 SCIP 2.1.1
5342*************************
5343
5344Features
5345--------
5346
5347- the pseudo objective propagator can be forced to propagate if active pricers are present; this can be done
5348 if for all (known or unknown) variables follows that: they have positive (negative) objective coefficient
5349 and the global lower (upper) bound is zero.
5350
5351Performance improvements
5352------------------------
5353
5354- improvements in undercover heuristic
5355- improve SCIPintervalSolveBivariateQuadExpressionAllScalar() for ax=0 case if x has 0 in the interval for the linear coef.
5356- better domain propagation for quadratic constraints that consist of `non-overlapping` bilinear terms only
5357- ensure that a fixing of a variable in an abspower constraint is propagated to a fixing of the other variable
5358- improvements in undercover heuristic, e.g., bound disjunction constraints are considered when setting up the covering problem
5359
5360Interface changes
5361-----------------
5362
5363### Changed parameters
5364
5365- changed parameter `propagating/pseudoobj/maxcands` to `propagating/pseudoobj/minuseless` (see prop_pseudoobj.c)
5366 due to revision of the pseudo objective propagator
5367
5368### New parameters
5369
5370- added parameters `heuristics/undercover/coverbd` and `heuristics/undercover/fixingorder`
5371
5372Fixed bugs
5373----------
5374
5375- fixed numeric issue in aggregations
5376- fixed pseudo cost computation
5377- fixed bug with setting type of slack variables to be implicitly integral
5378- fixed bug when copying problem data in c++ case returned with the result `SCIP_DIDNOTRUN`
5379- fixed computation of counter which state the changes since the last call of a presolver
5380- fixed handling of unbounded solutions, including double-checking their feasibility and that the primal ray is a
5381 valid unboundedness proof and reoptimizing the LP with modified settings if the solution is not feasible
5382- fixed compilation issues with negate() function in intervalarith.c on exotic platforms
5383- fixed bug in SCIPsortedvecDelPos...() templates
5384- pseudo objective propagator does not propagate it active pricers are present
5385- fixed bug in heur_shiftandpropagate.c concerning the treatment of unbounded variables
5386- workaround for trying to add variable bounds with to small coefficients
5387
5388- Reading and Writing:
5389 - gams writer now also substitutes $-sign from variable/equation names
5390 - fixed bug in reader_mps.c: INTEND marker is now also written, if COLUMNS section ends with non-continous variables
5391 - fixed bug in flatzinc reader w.r.t. boolean expressions
5392
5393- Constraints:
5394 - fixed constraint flags evaluation within the ZIMPL reader (reader_zpl.c)
5395 - fixed bug in SCIPmakeIndicatorFeasible() in cons_indicator.c
5396 - fixed bug with conflict clause modification in cons_indicator
5397 - fixed bug in cons_bounddisjunction with uninitialized return values
5398 - fixed bug in cons_orbitope with calling conflict analysis
5399 - fixed bug in nlpi_oracle w.r.t. changing linear coefs in a NLP constraint
5400
5401@section RN210 SCIP 2.1.0
5402*************************
5403
5404Features
5405--------
5406
5407- New original solution storage capability, which allows transfering solutions between SCIP runs
5408- SCIP-CPX is now threadsafe
5409- comparison of solutions now also works for original solutions
5410- can now compute the relative interior point of the current LP
5411- interval arithmetics for power, log, exp, bivariate quadratic expressions should be rounding safe now
5412- LP iterations in resolving calls can now be limited w.r.t. the average number of LP iterations in previous calls
5413 (after the root node); this is currently only done for the initial LP solve at a node and the corresponding parameter
5414 resolveiterfac is set to -1 (no limit) per default
5415- it is now possible in `SCIP_STAGE_TRANSFORMED` to call SCIPaddVarLocks() (i.e. to lock variables in initialization methods)
5416- changed computation of optimality gap which is now done in the same way as described in the MIPLIB 2010 paper: the gap
5417 is 0, if primalbound (pb) and dualbound (db) are equal (within tolerances), it is infinity if pb and db have opposite
5418 signs and (this changed), if both have the same sign, the difference between pb and db is devided by the minimum of
5419 the absolute values of pb and db (instead of always the dual bound)
5420- functionality to use the bound flipping ratio test of SoPlex is available (requires at least version 1.5.0.7)
5421- there exists now a solution candidate store for the original problem; during transformation these solutions are tried;
5422 during free the transformed problem the best feasible solution of the transformed problem are copied to the solution
5423 candidate store of the original problem; this useful if you solve several problems iteratively, solutions get now
5424 carried over automatically.
5425- reworked concept of lazy bounds: they can now also be used for problems where constraints and objective together
5426 ensure the bounds; to allow this also for diving heuristics that might change the objective and thus destroy this
5427 property, lazy bounds are explicitly put into the LP during diving and removed afterwards
5428- `SCIP_HASHMAP` now works also without block memory
5429- The variable deletion event is now a variable specific event and not global, anymore.
5430- All timing flags are now defined type_timing.h.
5431- all C template files are now called <plugintype>_xyz.{c,h} instead of <plugintype>_xxx.{c,h}
5432
5433- Separators and Cuts:
5434 - reorganized computation of scores in cut filtering: instead of the computation at the time of addition, scores are now
5435 only computed w.r.t. the current LP solution and when cut filtering is performed; one can now fill the cut storage
5436 with cuts that were separated for different solutions
5437 - New separator for close cuts and a new function to compute relative interior points of the LP
5438 - added first version of sepa_closecuts.{c,h} to separate cuts w.r.t. a point that is closer to the integral polyhedron
5439
5440- Constraints:
5441 - implement possibility to force a restart in cons_indicator if enough indicator variables have been fixed
5442 - the xor constraint handler can now parse its constraints
5443 - the bounddisjunction constraint handler can now parse its constraints
5444 - the knapsack, setppc and soc constraint handler can now parse their constraints
5445 - the varbound constraint handler can now parse its constraints
5446 - added beta version of variable deletion: for branch-and-price application, variables can now be completely deleted
5447 from the problem; variables that are deletable have to be marked with SCIPvarMarkDeletable(), constraint handlers can
5448 implement the new `SCIP_DECL_DELVARS` callback that should remove variables from the constraints; at the moment, only
5449 the linear, the setppc and the knapsack constraint handler support this callback; furthermore, when using this
5450 feature, all used plugins have to capture and release variables they store in their data, this is currently only done
5451 for the aforementioned constraint handlers as well as the and, the varbound and the logicor constraint handler; for
5452 more details about this feature, see the FAQ
5453 - added pseudoboolean constraint handler (cons_pseudoboolean.{c,h})
5454 - added first version of cons_disjunction.{c,h} which allows a disjunction of constraints
5455 - added constraint handler for (absolute) power constraints (cons_abspower.{c,h}) to handle equations like z = sign(x)abs(x)^n, n > 1
5456
5457- Heuristics:
5458 - new heuristic vbounds which use the variables lower and upper bounds to fix variable and performs a neighborhood search
5459 - added vbound heuristic (heur_vbounds.{c,h})
5460 - added clique heuristic (heur_clique.{c,h})
5461
5462- Reading and Writing:
5463 - added writing for wbo files
5464 - added writing for pip files (linear, quadratic, polynomial nonlinear, polynomial abspower, polynomial bivariate, and
5465 and constraints)
5466 - CIP format variable characters defined, e.g. `SCIP_VARTYPE_INTEGER_CHAR`
5467 - Improved support for wbo format for weighted PBO problems, IBM's xml-solution
5468 format and pip and zimpl format for polynomial mixed-integer programs
5469 - New reader for (standard) bounds on variables
5470 - Extended reader for CIP models to handle various new constraints, including all types of linear constraints
5471 - flatzinc reader is now capable to read cumulative constraints
5472 - changed opb(/wbo) reader which now creates pseudoboolean constraints instead of linear- and and-constraints, only a
5473 non-linear objective will create and-constraints inside the reader and while reading a wbo file the topcost constraint
5474 is created as well
5475 - added clock for determine the time for reading
5476 - added reader for variable bounds (reader_bnd.{c,h})
5477 - Removed method SCIPreadSol(); call solution reading via SCIPreadProb() which calls the solution reader for .sol files.
5478
5479- Nonlinear:
5480 - Major extensions for nonlinear CIP, new option for n-ary branching on nonlinear variables (within pseudocost branching rule)
5481 - added BETA version of constraint handler for nonlinear constraints (cons_nonlinear.{c,h}) to handle nonlinear
5482 equations given by algebraic expressions using operands like addition, multiplication, power, exp, log, bivariate
5483 nonlinear constraints; currently no trigonometric functions
5484 - added BETA version of constraint handler for bivariate nonlinear constraints (cons_bivariate.{c,h}) to compute tight
5485 estimators for 1-convex and convex-concave bivariate nonlinear functions (given as expression tree)
5486 - the gams writer can now write nonlinear, abspower and bivariate constraints
5487 - Extended writer for GAMS and pip format to write more types of nonlinear constraints
5488 - the pip and zimpl reader now create nonlinear constraints for polynomials of degree > 2
5489
5490- Presolving:
5491 - new dual presolving methods in cons_setppc and cons_logicor
5492 - new presolving step `removeConstraintsDueToNegCliques` in locigor constraint handler which updates logicor constraints
5493 to setppc constraints if a negated clique inside this constraint exist, by default is off
5494 - new presolving step in cons_knapsack (detectRedundantVars, deleteRedundantVars) which determines redundant variables
5495 in knapsack constraint with or without using clique information
5496 - cons_logicor is now able to replace all aggregated variables in presolving by there active or negation of an active
5497 variable counterpart
5498 - prop_pseudoobj is now working in presolving as well
5499 - implement presolving in exitpre() in cons_orbitope and cons_indicator
5500
5501- Propagators:
5502 - added counter for number calls and timing for resolve propagation calls for constraint handler and propagators
5503 - Propagators are now also called in node presolving
5504 - the probing presolver presol_probing.{c.h} is now a propagator prop_probing.{c,h}, all corresponding parameters moved as well
5505 - the redcost separator sepa_redcost.{c.h} is now a propagator prop_redcost.{c,h}, all corresponding parameters moved as well
5506 - outsourced propAndSolve() method in solve.c which calls domain propagation and solving of the lp and relaxation
5507
5508- Statistic:
5509 - solutions which are given by the user from the outside are now marked by `#` in the output
5510 - the `Solving Time` is now spitted into presolving, solving and reading time
5511 - Presolvers section has new column `AddCons` which states the number of added constraint
5512 - Constraints section has new column named \#ResProp which show the number of resolve propagation calls of certain
5513 constraint handler
5514 - Constraint Timing section has a new column \#ResProp which states the time spend in resolve propagation method of the
5515 constraint handler
5516 - improved output of propagators in display statistics
5517 - new section `Propagator Timing` which shows the time spend in different callbacks of the propagator
5518 - rearranged first two columns of Propagators section; \#Propagate and \#ResProp stating the number of call for
5519 propagation and resolve propagation; the Time column is moved into the new section Propagator Timings
5520 - Constraints section has new column named `MaxNumber` which the maximum number of active constraint of a certain
5521 constraint handler
5522 - added two columns `Time-0-It` and `Calls-0-It` in the LP section which states the number of LP call and time spend for
5523 solving LPs with zero iterations (only refactorization)
5524 - The display of statistics for presolvers, propagators, constraints and LP solving has changed.
5525
5526Performance improvements
5527------------------------
5528
5529- Reorganized filtering process of separation storage (allows adding cuts for different solutions)
5530- Improved presolving for various constraint handlers
5531- Improved propagation methods for variable bound constraints
5532- Improved performance for quadratic constraints
5533- performance improvements in prop_vbounds
5534- child selection rules now get also applied when the relaxation value is equal to the bound changed in branching
5535- added dual reduction to cons_cumulative.c
5536- for continuous variables, the pseudo costs update and the pscost branching rule now use the same strategies for
5537 updating the pseudo costs and estimating the improvement in the LP bound
5538- only perform probing if the variables are locked
5539- performance and memory consumption improvements in xmlparse.c
5540- Improved knapsack cover cuts
5541- avoid very long separation times of LEWIs in cons_knapsack for very large minimal covers
5542- used SCIPallocMemoryArray() instead of SCIPallocBlockMemoryArray() which leads to fewer memory consumption in
5543 getLiftingSequence() in cons_knapsack, also improved cache use bei using an extra array instead blockmemory chunks
5544- switched FASTMIP from 1 to 2 for CPLEX and changed default pricing rule back to steepest edge pricing instead of
5545 quickstart steepest edge pricing
5546- made sorting method more robust
5547- LNS heuristics now use SCIPcopy() by default
5548- considering inactive variables in undercover heuristic; limiting effort for solving covering problem
5549- if during probing mode the LP relaxation is solved from scratch, e.g., when calling the shiftandpropagate heuristic
5550 before root node solving, then we clear the resulting LP state, since it might be a bad starting basis for the next
5551 solve of the LP relaxation (controlled by new parameter `lp/clearinitialprobinglp`)
5552- included LP simplifier into SoPlex LP interface, applied when solving from scratch (lpi_spx.cpp)
5553- new presolving steps in varbound constraint handler, tightening bounds, coefficients, sides and pairwise presolving
5554
5555Interface changes
5556-----------------
5557
5558- Miscellaneous:
5559 - The emphasis setting types now distinguish between plugin-type specific parameter settings (default, aggressive, fast, off),
5560 which are changed by SCIPsetHeuristics/Presolving/Separating(), and global emphasis settings (default, cpsolver, easycip,
5561 feasibility, hardlp, optimality, counter), which can be set using SCIPsetEmphasis().
5562
5563### New and changed callbacks
5564
5565- added propagator timings `SCIP_PROPTIMING_BEFORELP`, `SCIP_PROPTIMING_DURINGLPLOOP` and `SCIP_PROPTIMING_AFTERLPLOOP` for
5566 all propagation callbacks (see propagators and constraint handlers) which lead to calling the propagation methods of a
5567 propagator before the lp is solved, during the lp loop and after the lp solving loop
5568
5569- Conflict Analysis:
5570 - Added parameter `separate` to conflict handler callback method SCIP_DECL_CONFLICTEXEC() that defines whether the conflict
5571 constraint should be separated or not.
5572
5573- Constraint Handler:
5574 - The new constraint handler callback SCIP_DECL_CONSDELVARS() is called after variables were marked for deletion.
5575 This method is optional and only of interest if you are using SCIP as a branch-and-price framework. That means,
5576 you are generating new variables during the search. If you are not doing that just define the function pointer
5577 to be `NULL`.
5578 If this method gets implemented you should iterate over all constraints of the constraint handler and delete all
5579 variables that were marked for deletion by SCIPdelVar().
5580
5581- NLP Solver Interface:
5582 - The callbacks SCIP_DECL_NLPIGETSOLUTION() and SCIP_DECL_NLPISETINITIALGUESS() got new parameters to get/set values of
5583 dual variables.
5584 - The callback SCIP_DECL_NLPICOPY() now passes the block memory of the target SCIP as an additional parameter.
5585
5586- Presolving:
5587 - New parameters `isunbounded` and `isinfeasible` for presolving initialization (SCIP_DECL_CONSINITPRE(),
5588 SCIP_DECL_PRESOLINITPRE(), SCIP_DECL_PROPINITPRE()) and presolving deinitialization (SCIP_DECL_CONSEXITPRE(),
5589 SCIP_DECL_PRESOLEXITPRE(), SCIP_DECL_PROPEXITPRE()) callbacks of presolvers,
5590 constraint handlers and propagators, telling the callback whether the problem was already declared to be
5591 unbounded or infeasible. This allows to avoid expensive steps in these methods in case the problem is already
5592 solved, anyway.
5593
5594 Note, that the C++ methods
5595 - scip::ObjConshdlr::scip_presol() corresponding to SCIP_DECL_CONSPRESOL()
5596 - scip::ObjConshdlr::scip_initpre() corresponding to SCIP_DECL_CONSINITPRE()
5597 - scip::ObjPresol::scip_initpre() corresponding to SCIP_DECL_PRESOLINITPRE()
5598 - scip::ObjProp::scip_initpre() corresponding to SCIP_DECL_PROPINITPRE()
5599 - scip::ObjConshdlr::scip_exitpre() corresponding to SCIP_DECL_CONSEXITPRE()
5600 - scip::ObjPresol::scip_exitpre() corresponding to SCIP_DECL_PRESOLEXITPRE()
5601 - scip::ObjProp::scip_exitpre() corresponding to and SCIP_DECL_PROPEXITPRE()
5602 are virtual functions. That means, if you are not adding the new parameters, your code will still compile, but these methods are not executed.
5603 - Propagators are now also called in during presolving, this is supported by the new callback methods SCIP_DECL_PROPINITPRE(),
5604 SCIP_DECL_PROPEXITPRE(), and SCIP_DECL_PROPPRESOL().
5605 - The new parameters `nnewaddconss` and `naddconss` were added to the constraint handler callback method SCIP_DECL_CONSPRESOL()
5606 and the presolver callback method SCIP_DECL_PRESOLEXEC(). These parameters were also added to corresponding C++ wrapper
5607 class methods (scip_presol() in objconshdlr.h and scip_exec() in objpresol.h)
5608
5609- Problem Data:
5610 - The callback SCIP_DECL_PROBCOPY() got a new parameter `global` to indicate whether the global problem or a local version is copied.
5611
5612### Deleted and changed API methods
5613
5614- implemented SCIPlpiGetPrimalRay() in SoPlex interface that has become available with SoPlex version 1.5.0.2
5615- allowed calling SCIPgetRowSolActivity() in `SCIP_STAGE_SOLVED`, since LP is still available
5616- various extensions and modifications for expressions and expression trees (too much to state here)
5617- The result value `SCIP_NEWROUND` has been added, it allows a separator/constraint handler to start a new separation round
5618 (without previous calls to other separators/conshdlrs).
5619- SCIPcalcNodeselPriority() got a new parameter `branchdir`, which defines the type of branching that was performed: upwards, downwards, or fixed.
5620
5621- Constraint Handlers:
5622 - Method SCIPincludeQuadconsUpgrade() of quadratic constraint handler got new parameter `active` to indicate whether the upgrading method is active by default.
5623 - Method SCIPseparateRelaxedKnapsack() in knapsack constraint handler got new parameter `cutoff`, which is a pointer to store whether a cutoff was found.
5624
5625- Nonlinear expressions, relaxation, and solver interface:
5626 - SCIPcreateNLPSol() now creates a `SCIP_SOL` that is linked to the solution of the current NLP relaxation
5627 - Various types and functions dealing with polynomial expressions have been renamed to use the proper terms `monomial` and
5628 `polynomial` in nonlinear expressions (nlpi/∗expr*); results in many renamings of types, structs and methods.
5629 - The methods SCIPnlpGetObjective(), SCIPnlpGetSolVals(), and SCIPnlpGetVarSolVal() have been removed, use SCIPgetNLPObjval(),
5630 SCIPvarGetNLPSol() and SCIPcreateNLPSol() to retrieve NLP solution values instead.
5631 SCIPcreateNLPSol() now returns an error if NLP or NLP solution is not available
5632 - Removed methods SCIPmarkRequireNLP() and SCIPisNLPRequired(), because the NLP is now always constructed if nonlinearities
5633 are present.
5634 - SCIPgetNLP() has been removed and NLP-methods from pub_nlp.h have been moved to scip.h, which resulted in some renamings, too.
5635 - renamed SCIPexprtreeEvalSol() to SCIPevalExprtreeSol() and now located in scip.h.
5636 - renamed SCIPexprtreeEvalIntLocalBounds() to SCIPevalExprtreeLocalBounds() and now located in scip.h.
5637 - renamed SCIPexprtreeEvalIntGlobalBounds() to SCIPevalExprtreeGlobalBounds() and now located in scip.h.
5638 - The functions SCIPnlpiGetSolution() and SCIPnlpiSetInitialGuess() got additional arguments to get/set dual values.
5639 - The method SCIPgetNLPI() got a new parameter `nlpiproblem`, which is a pointer to store the NLP solver interface problem.
5640
5641- Timing:
5642 - SCIPincludeProp() got additional parameters to set the timing mask of the propagator and the new callbacks and parameters
5643 related to calling the propagator in presolving.
5644 - SCIPincludeConshdlr() got additional parameters to set the variable deletion callback function and the timing mask for
5645 propagation.
5646 - removed parameters timelimit and memorylimit from SCIPapplyRens()
5647 - The parameters `timelimit` and `memorylimit` were removed from SCIPapplyRens().
5648
5649- Problem Data:
5650 - The method SCIPcopyProb() got a new parameter `global` to indicate whether the global problem or a local version is copied.
5651
5652- Writing and Parsing Constraints:
5653 - The methods SCIPwriteVarName(), SCIPwriteVarsList(), and SCIPwriteVarsLinearsum() got a new boolean parameter `type`
5654 that indicates whether the variable type should be written or not.
5655 - The methods SCIPparseVarName() and SCIPparseVarsList() got a new output parameter `endptr` that is filled with the position
5656 where the parsing stopped.
5657 - The method SCIPwriteVarsList() got additionally a new parameter `delimiter` that defines the character which is used for delimitation.
5658
5659- Variables:
5660 - SCIPmarkDoNotMultaggrVar()/SCIPvarMarkDoNotMultaggr() now allow to mark negated and aggregated variables
5661 - SCIPgetVarCopy() got a new parameter `success` that will be FALSE if method is called after problem creation stage and no hash map is
5662 given or no image for the given variable is contained in the given hash map.
5663 - SCIPchgVarType() got an extra boolean parameter to store if infeasibility is recognized while upgrading a variable from continuous
5664 type to an integer type.
5665 - SCIPdelVar() got a new parameter `deleted`, which stores whether the variable was successfully marked to be deleted.
5666
5667### New API functions
5668
5669- information about the quality of the solution of an LP (currently the condition number of the basis matrix) can now be:
5670 + requested from the LPI (currently only available for CPLEX): methods SCIPlpiGetRealSolQuality() and
5671 + SCIPprintLPSolutionQuality() command display lpsolquality in interactive shell display column lpcond to show
5672 + estimate on condition number, if available
5673- SCIPround() and SCIPfeasRound() to round to nearest integer
5674- SCIPsortRealRealIntInt() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
5675- SCIPsortRealIntLong(), SCIPsortPtrPtrRealInt() and corresponding sorting/inserting/deleting methods in
5676 pub_misc.h and necessary defines in misc.c
5677- SCIPcomputeLPRelIntPoint() to compute relative interior point of the current LP
5678- SCIPstartSolvingTime() and SCIPstopSolvingTime() which can be used to start or stop the solving time clock
5679- SCIPstrToRealValue() and SCIPstrCopySection() in pub_misc.h; these methods can be used to convert a string
5680 into a `SCIP_Real` value and to copy a substring.
5681- SCIPgetBinvarRepresentatives() which gets binary variables that are equal to some given binary variables,
5682 and which are either active, fixed, or multi-aggregated, or the negated variables of active, fixed, or multi-aggregated variables
5683- SCIPhasPrimalRay() and SCIPgetPrimalRayVal() that return whether a primal ray is stored and which value a
5684 given variable has in the primal ray, respectively
5685- SCIPsetConsModifiable()
5686- SCIPsetParam() which is a generic parameter setter method, independent of the parameter type
5687- SCIPpropInitpre(), SCIPpropExitpre(), SCIPpropPresol() which initializes, exists and executes the presolving phase
5688- SCIProwGetAge() to access the age of a row (pub_lp.h/lp.c)
5689- SCIPsolGetOrigObj() in pub_sol.h which returns for a solution in the original problem space the objective value
5690- SCIPretransformSol() in scip.h that allows to retransform a solution to the original space
5691- SCIPlpiClearState() to LP interfaces for clearing basis information in the LP solver
5692- SCIPgetSubscipDepth() to access the depth of the current SCIP as a copied subproblem
5693- SCIPdebugAddSolVal() and SCIPdebugGetSolVal() to add/get values to/from a debug solution
5694- SCIPsepastoreRemoveInefficaciousCuts() to remove non-efficious cuts from the separation storage
5695
5696- Nodes:
5697 - SCIPnodeGetParent() to get parent node of a node
5698 - SCIPnodesSharePath() in pub_tree.h that determines whether two nodes are on the same leaf-root path
5699 - SCIPnodesGetCommonAncestor() in pub_tree.h that finds the common ancestor node for two given nodes
5700
5701- Read and Write:
5702 - SCIPgetReadingTime() which returns the time for reading in seconds
5703 - SCIPparseVarsLinearsum(), SCIPparseVarsPolynomial() and SCIPwriteVarsPolynomial() and for writing and
5704 parsing polynomials in constraint handler writing/parsing methods
5705
5706- Memory:
5707 - SCIPcreateMesshdlrPThreads() and SCIPfreeMesshdlrPThreads() for allocating and deleting necessary memory
5708 for message handlers for parallel pthread version
5709 - SCIPallocClearMemoryArray() and BMSallocClearMemoryArray() for allocating cleared memory arrays in scip.h and memory.h
5710
5711- Intervals:
5712 - SCIPintervalPowerScalarInverse() to solve an equation y = x^p for given bounds on y and scalar exponent p
5713 - SCIPintervalQuadBivar() to compute tight bounds on a bivariate quadratic form
5714 - SCIPintervalSolveBivariateQuadExpressionAllScalar() to compute tight bounds on the solutions of a bivariate quadratic equation
5715
5716- Variables:
5717 - SCIPcomputeVarCurrent{L,U}b{Local,Global}() to compute local or global lower or upper bounds of a
5718 multiaggregated variable from the bounds of the aggregation variables
5719 - SCIPbranchVarValNary() for n-ary variable branching
5720 - SCIPgetNegatedVars() which returns all negated variables for a given array of variables, if the negated
5721 variables are not existing yet, they will be created
5722 - SCIPgetNTotalVars() that returns the total number of created vars, icluding variables that were deleted in the meantime
5723 - SCIPvarGetHashkey(), SCIPvarIsHashkeyEq(), SCIPvarGetHashkeyVal() in pub_var.h which can be used for `SCIP_HASHTABLE` of variables
5724 - SCIPvarGetNBdchgInfosLb() and SCIPvarGetNBdchgInfosUb() in pub_var.h returning the number of lower or upper bound changes on the active path
5725 - SCIPvarGetBdchgInfoLb() and SCIPvarGetBdchgInfoUb() returning the bound change information at the given position
5726 - SCIPvarMarkDeletable() to mark a variable to be deletable completely from the problem (for
5727 branch-and-price); can only be called before the variable is added to the problem
5728 - SCIPvarMarkNotDeletable() that marks a variable to be non-deleteable (used within SCIP for forbidding
5729 deletion of variables contained in solution, LP bases, (multi)aggregation, ...)
5730 - SCIPvarIsDeletable() that returns whether a variable is marked to be deletable (each variable is per default non-deletable)
5731
5732- NLP:
5733 - SCIPgetNLPVarsNonlinearity() to get for each variable in the NLP the number of NLP rows in which this variable appears in a nonlinear way
5734 - SCIPnlrowGetDualsol(), SCIPgetNLPVarsLbDualsol(), SCIPgetNLPVarsUbDualsol() to retrieve dual values from an NLP solution
5735 - SCIPgetNLPFracVars() to get the fractional variables in an NLP solution
5736
5737- Propagator:
5738 - SCIPpropSetPresolPriority() which changes the presolving priority of a given propagator
5739 - SCIPpropGetPresolPriority(), SCIPpropGetPresolTime(), SCIPpropWasPresolDelayed(), SCIPpropGetNFixedVars(),
5740 SCIPpropGetNAggrVars(), SCIPpropGetNChgVarTypes(), SCIPpropGetNChgBds(), SCIPpropGetNAddHoles(), SCIPpropGetNDelConss(),
5741 SCIPpropGetNAddConss(), SCIPpropGetNUpgdConss(), SCIPpropGetNChgCoefs(), SCIPpropGetNChgSides(), SCIPpropGetTimingmask(),
5742 SCIPpropDoesPresolve() which return corresponding presolving information
5743 - SCIPpropGetNRespropCalls() and SCIPconshdlrGetNRespropCalls() which return the number of times a
5744 propagator or a constraint handler was called for resolving a propagation
5745 - SCIPpropGetRespropTime() and SCIPconshdlrGetRespropTime() which return time spent for resolving a
5746 propagation within a propagator or a constraint handler
5747 - SCIPcheckCumulativeCondition(), SCIPpropCumulativeCondition() and SCIPrespropCumulativeCondition() in
5748 cons_cumulative.h; these methods can be used to check, propagate, or resolve the propagation of a cumulative condition
5749 - SCIPpropagateCutoffboundVar() in prop_pseudoobj.h which can be used to propagate the cutoff bound for the given variables
5750
5751- Constraints:
5752 - added to linear constraint handler SCIPsetUpgradeConsLinear(), which (de-)activates the possibility to
5753 upgrade a linear constraint to a specialized linear constraint (e.g. knapsack)
5754 - SCIPconvertCutsToConss() and SCIPcopyCuts() to scip.{c,h} for copying cuts to linear constraints
5755 - SCIPaddCoefLogicor() to add a variable to a logic or constraint
5756 - SCIPfindOrigCons() which return a original constraint with the given name or `NULL`
5757 - SCIPconshdlrGetNAddConss() which returns the number of added constraints during presolving by a given constraint handler
5758 - SCIPpresolGetNAddConss() which returns the number of added constraints during presolving by a given presolver
5759
5760### Command line interface
5761
5762- New funtionalities in the interactive shell (modify current CIP instance, write NLP relaxation)
5763- added dialog `write nlp` to write current NLP relaxation to a file
5764- new dialog `change freetransproblem` to free transformed problem in the interactive shell before changing the problem
5765- it is possible to change bounds of a variable in the interactive shell
5766- it is possible to add a constraint to a problem in the interactive shell
5767
5768### Interfaces to external software
5769
5770- Improved SOPLEX interface (LP simplifier)
5771- Improved CPLEX interface, including measures for numerical stability
5772
5773### Changed parameters
5774
5775- change default value of parameter `nodeselection/restartdfs/selectbestfreq` 100
5776- moved parameters for pseudoboolean constraints from opb-reader to pseudoboolean constraint handler
5777- changed possible parameter values of `branching/pscost/strategy` from `bri` to `cdsu`: default is now `u`, i.e., to
5778 estimate the LP gain by a branching for external branching candidates (esp. continuous variables) the same way as
5779 their pseudo costs are updated
5780- added possible value `d` for `constraints/soc/nlpform` to choose a convex division form for SOC constraint
5781 representation in NLP
5782- renamed parameter `constraints/quadratic/linearizenlpsol` to `constraints/quadratic/linearizeheursol` and do
5783 linearizations in every solution found by some heuristic
5784- renamed parameter `constraints/quadratic/mincutefficacyenfo` to `constraints/quadratic/mincutefficacyenfofac` and
5785 interpret it as a factor of the feasibility tolerance
5786- removed fastmip setting 2, which means the dualsolution would not be calculated but because SCIP always asks for the
5787 dual solution, the lp would be reoptimized to calculate them; so it had no real effect
5788- all parameters in cons_indicator and cons_sos1 have been converted to lower case!
5789- changed default value of parameter `separating/gomory/maxroundsroot` to 10
5790- changed default value of parameter `separating/gomory/maxsepacutsroot` to 50
5791- removed parameter `heuristics/subnlp/nlpsolver`, use `nlp/solver` instead
5792
5793### New parameters
5794
5795- `branching/delaypscostupdate` to delay the update of pseudo costs for continuous variables behind the separation round: default is TRUE
5796- `branching/lpgainnormalize` to set the strategy how the LP gain for a continuous variable is normalized when updating the
5797 variables pseudocosts: default is to divide LP gain by reduction of variable's domain in sibling node
5798- `branching/pscost/nchildren` and `branching/pscost/nary*` to enable and customize n-ary branching on
5799 external branching candidates (e.g., in spatial branching for MINLP)
5800- `conflict/bounddisjunction/continuousfrac` which defines the maximum percantage of continuous variables
5801 within a conflict create by the bounddisjunction conflict handler
5802- `conflict/separate` which enables or disables the separation of conflict constraints
5803- `constraints/{nonlinear,quadratic,soc,abspower}/sepanlpmincont` to specify minimal required fraction
5804 of continuous variables in problem to enable linearization of convex constraints in NLP relaxation solution in root
5805- `constraints/indicator/forcerestart` and `constraints/indicator/restartfrac` to control forced restart in cons_indicator
5806- `constraints/indicator/generatebilinear` to generate bilinear (quadratic) constraints instead of indicator constraints
5807- `constraints/indicator/maxconditionaltlp` to enable a quality check for the solution of the alternative LP
5808- `constraints/indicator/removeindicators` to remove indicator constraints if corresponding vub has been added
5809- `constraints/linear/nmincomparisons` and `constraints/linear/mingainpernmincomparisons` to influence
5810 stopping criterium for pairwise comparison of linear constraints
5811- `constraints/pseudoboolean/decompose`, for pseudoboolean constraints to transform pseudoboolean constraints into linear- and and-constraints
5812- `constraints/quadratic/binreforminitial` to indicate whether linear (non-varbound) constraints added due to reformulation of products with
5813 binary variables in a quadratic constraints should be initial (if the quadratic constraint is initial), default is FALSE
5814- `constraints/quadratic/checkfactorable` to disable check for factorable quadratic functions (xAx = (ax+b)*(cx+d)) in quadratic constraints
5815 and not to use of this information in separation (generates lifted tangent inequalities according to Belotti/Miller/Namazifar if also
5816 linear vars are present)
5817- `constraints/quadratic/disaggregate` to split a block-separable quadratic constraint into several quadratic constraint
5818- `constraints/quadratic/maxproprounds` and `constraints/quadratic/maxproproundspresolve` to limit the
5819 number of propagations rounds for quadratic constraints within one propagation round of SCIP solve or during SCIP presolve
5820- `constraints/varbound/presolpairwise` that allows pairwise presolving of varbound constraints, default is TRUE
5821- `heuristics/shiftandpropagate/onlywithoutsol` to switch whether the heuristic should be called in case a primal solution is already present
5822- `limit/maxorigsol` which defines the size of the solution candidate store (default value is 10)
5823- `lp/resolverestore` controlling how LP solution is restored after diving: if TRUE by resolving them,
5824 if FALSE by buffering them; if `lp/freesolvalbuffers` is TRUE, we free the buffer memory each time (FALSE by default)
5825- `lp/clearinitialprobinglp` to clear LP state at end of probing mode, if LP was initially unsolved
5826- `lp/resolveitermin` and `lp/resolveiterfac` to limit the number of LP iterations in resolving calls:
5827 resolveiterfac is a factor by which the average number of iterations per call is multiplied to get the limit, but the
5828 limit is at least resolveitermin; default is -1 (no limit) for resolveiterfac and 1000 for resolveitermin
5829- `lp/resolverestore` and `lp/freesolvalbuffers` possibility to buffer and restore LP solution after diving without
5830 having to resolve the LP; currently turned off, because performance impact is unclear;
5831- `misc/improvingsols` which states whether only solutions which have a better (or equal) primal bound
5832 as the best known are checked; this is of interest if the check of a solution is expensive; default value is FALSE
5833- `misc/resetstat` which state if the statistics should be reseted if the transformed problem is freed
5834 (in case of a benders decomposition this parameter should be set to FALSE) default value is TRUE
5835- `nodeselection/restartdfs/countonlyleafs` in node selector restart dfs which can be used to select the counting process of processed nodes
5836- `presolving/donotaggr` to deactivate aggregation of variables globally
5837- `pricing/delvars` and `pricing/delvarsroot` that define, whether variables created at a node / the
5838 root node should be deleted when the node is solved in case they are not present in the LP anymore
5839- `propagating/%s/maxprerounds` for all propagators which allows to change to maximal number of rounds
5840 of presolving where this propagator participates in
5841- `propagating/%s/presoldelay` for all propagators which allows to change if the presolving call of the given propagator should be delayed
5842- `propagating/%s/presolpriority` for all propagators which allows to change the priority of calling the given propagator
5843- `propagating/pseudoobj/propfullinroot` for allowing to propagate all variables in the root node,
5844 instead of stopping after `maxcands` which is set by a parameter as well
5845- `reading/gmsreader/bigmdefault` and `reading/gmsreader/indicatorreform` reader_gms is now able to write indicator
5846 constraints (reformulated either via big-M or sos1)
5847- `reading/gmsreader/signpower` to enable writing sign(x)abs(x)^n as the rarely used gams function signpower(x,n)
5848- `separating/closecuts/maxunsucessful` to turn off separation if we can not find cuts
5849- `timing/reading` to add reading time to solving time
5850
5851### Data structures
5852
5853- split off `PARAMEMPHASIS` from `PARAMSETTING` (in pub_paramset.c/paramset.c)
5854- new data structure `SCIP_STAIRMAP`
5855- add expression graph data structures and methods for reformulation, domain propagation, simple convexity check on
5856 nonlinear expressions and simplification for expression trees and graphs
5857
5858Testing
5859-------
5860
5861- New scripts for running tests with GAMS
5862- added scripts check_gams.sh, evalcheck_gams.sh and check_gams.awk and target `testgams` in Makefile
5863- adjusted all test scripts to use the same new optimality gap computation as in SCIP
5864- added Makefile option `VALGRIND=true` to enable running the SCIP checks (make test) through valgrind; valgrind errors
5865 and memory leaks are reported as fails
5866- moved *.test and *.solu files to subdirectory testset in check directory and adjusted test scripts
5867
5868Build system
5869------------
5870
5871### Makefile
5872
5873- Variables:
5874 - via `PARASCIP=true` as a `Makefile` option it is possible to compile SCIP threadsafe in DEBUG-mode, (in OPT-mode it's
5875 only necessary if non-default messagehandler or CppAD is used)
5876 - the `make` parameter `PARASCIP=true` leads to threadsafe message handlers where you need to call
5877 SCIPcreateMesshdlrPThreads() and SCIPmessageSetHandler()/SCIPmessageSetDefaultHandler() and SCIPfreeMesshdlrPThreads();
5878 therefore we need to link with pthread library
5879 - new variable $(INSTALLDIR) in Makefile which define installation directory for the libraries, $(INSTALLDIR)/lib/,
5880 binary, $(INSTALLDIR)/bin and include headers, $(INSTALLDIR)/include, the default value is the empty string
5881
5882- Linking:
5883 - Linking against Clp and Ipopt has been simplified. Only the directory where the
5884 package has been installed need to be provided now. For details see the INSTALL file.
5885 - to link against IPOPT, only the base directory of an Ipopt installation need to be specified now; additionally, if
5886 building with gnu compilers, the Ipopt libraries directory is stored in the SCIP binary, which should make it easier
5887 to run with Ipopt shared libraries
5888 - to link against Clp, only the base directory of an Clp installation needs to be specified now
5889
5890- Targets:
5891 - New targets `(un)install` in Makefile, support for valgrind in testing environment
5892 - new target `make libs` which compiles only the libraries
5893 - new target in Makefile `install` performs `make` and copies using the install command the include headers, binary, and
5894 libraries
5895 - new target in Makefile `uninstall` removes libraries, binary and include headers form `INSTALLDIR`
5896 - removed target `lintfiles`, this target is now imitated by the `lint` target and a none empty variable `FILES`
5897
5898Fixed bugs
5899----------
5900
5901- fixed bug in copying if the target SCIP already is in solving stage: it might be that the copy of a variable cannot be found/created
5902- fixed bug trying to print big messages bigger than `SCIP_MAXSTRLEN`
5903- fixed bug w.r.t. counting feasible solutions and turned of sparse solution test
5904- LP solution status is now checked when checking root LP solution. Otherwise, due to different time measurements, it
5905 might happen that the LP solving was stopped due to the time limit, but SCIP did not reach the limit, yet.
5906- fixed bug trying to tighten multiaggregated variables, which have only one active representation and this variable is already tightened
5907- fixed possible buffer overrun in tclique_graph.c
5908- fixed issue with interactive shell in case (user) plugins are included after the default plugins
5909- fixed bug where mutiaggregating leads to an aggregation and both variables were of implicit or integral type
5910- fixed bug in conflict.c, where LPi was manipulated, but not marked as not solved
5911
5912- Tree:
5913 - fixed assertion in tree.c w.r.t. node estimation
5914 - fixed bug in debug.c: removed tree nodes had not been checked if they were pruned due to an incumbent solution found by a diving heuristic
5915
5916- Bounds:
5917 - fixed bug which occured when changing a bound in the solving stage when this variables got upgraded from continuous to
5918 a integer type, where the bounds of this variable were still not integral; due to that SCIPchgVarType() has changed (see above)
5919 - fixed bug in handling of lazy bounds that resulted in putting the bounds explicitly into the LP
5920
5921- Separation:
5922 - fixed assert in sepa_clique.c which is currently not valid because implicit binary variables in cliques are ignored
5923 - fixed bug in sepa_zerohalf.c concerning inconsistent construction of solution array of variables and fixed wrong assert about variable bounds
5924
5925- Constraints:
5926 - fixed not correct merging of variable in logicor constraint handler and changed the name of the method to a common
5927 name used by other constraint handlers too(findPairsAndSets->mergeMultiples)
5928 - fixed bugs in changing the initial and checked flags for constraints in original problem
5929 - fixed bug in cons_linear.c, when scaling a constraint maxabscoef was not set correctly, furthermore the correction of
5930 maxabscoef was not handled correctly
5931 - fixed bug in cons_indicator.c trying to copy a constraint where the pointer to the linear constraint did not point to
5932 the already transformed linear constraint (, happend when SCIPcopy() is used after transforming before presolving)
5933 - fixed numerical bug in linear constraint handler: polishing of coefficients after fixing variables led to wrong
5934 results for continuous variables fixed to a close-to-zero value.
5935 - fixed bug in cons_bounddisjunction where branching on multiaggregated variables was tried while all aggregation variables are fixed
5936 - fixed bug in presolving of cons_logicor.c: adding variable implications can lead to further reductions; added call to applyFixings()
5937 - fixed bug in cons_countsols.c w.r.t. none active variables
5938 - fixed bug in cons_linear.c, scaling could have led to wrong values
5939
5940- Reader:
5941 - fixed bug in reader_fzn.c w.r.t. cumulative constraints
5942 - fixed bug in reader_mps.c: if a variables first occurence is in the bounds section, then the corresponding variable bound was lost
5943 - fixed several issues in flatzinc reader
5944 - deactived checking of zero solution in Zimpl reader when no starting values are provided
5945 - reader_lp is now able to read lines longer than 65534 characters
5946
5947- Memory:
5948 - fixed bug in copying NLPI interfaces that use block-memory (NLPI copy used block memory from source SCIP)
5949 - fixed memory leak in reader_pip.c
5950 - fixed memory leak in coloring part of maximum clique algorithm (tclique_coloring.c)
5951 - fixed memory leak in coloring part of maximum clique algorithm (tclique_coloring.c) in a better way
5952
5953- Numerics:
5954 - fixed bug which occured when the dual farkas multipliers were not available in the lpi because the LP could only be
5955 solved with the primal simplex due to numerical problems
5956 - fixed bug in ZI round heuristic that led to infeasible shiftings for numerically slightly infeasible rows with close-to-zero coefficients
5957 - fixed numerical issue in octane heuristic: close-to-zero values for ray direction could have led to bad computations
5958
5959- Propagation:
5960 - fixed bug in propagation of indicator constraints: cannot fix slack variable to 0 if linear constraint is disabled/not active
5961 - fixed bug in cons_linear.c while sorting the eventdatas during the binary variable sorting for propagation
5962 - fixed bug and wrong assert in heur_shiftandpropagate.c when relaxing continuous variables from the problem
5963 - fixed bug in cons_orbitope:resprop() for the packing case
5964 - fixed wrong changing of wasdelayed flag for propagators
5965 - fixed bug using wrong sign in infinity check in prop_pseudoobj
5966 - fixed bug in redcost propagator: can only be called if the current node has an LP
5967 - fixed bug w.r.t. infinity loop during propagation
5968
5969Miscellaneous
5970-------------
5971
5972- The interface contains several additional callback functions and parameters for plugins. Some effort may be required to compile your old
5973 projects with SCIP 2.1. For details see section `Changes between version 2.0 and 2.1` in the doxygen documentation.
5974
5975@page RN20 Release notes for SCIP 2.0
5976
5977@section RN202 SCIP 2.0.2
5978*************************
5979
5980Performance improvements
5981------------------------
5982
5983- improved twoopt-heuristic by considering larger search domains
5984- the SoPlex interface now has the capability to provide a primal ray, provided it is compiled against the next SoPlex release (>= 1.5.0.2)
5985- calculation of node priority now also works when variable's relaxation value is equal to a bound
5986- fixed issue w.r.t. calling primal heuristics after presolving detected infeasibility
5987
5988- Constraints:
5989 - fasten propagation in cons_knapsack.c due to negated clique partitions
5990 - recalculating only needed partitions in cons_knapsack.c, not always both
5991
5992- Memory:
5993 - reduced memory usage of shift-and-propagate heuristic
5994 - knapsack constraints are now separated faster; SCIPsolveKnapsackExactly() now works faster and requires less memory
5995 - fasten knapsack separation by replacing SCIPallocBuffer(Array) through SCIPallocBlockMemory(Array)
5996 - improved runtime and memory consumption in SCIPsolveKnapsackExactly() in cons_knapsack.c
5997
5998Fixed bugs:
5999----------
6000
6001- fixed `make/make.project`
6002- fixed wrong assert in plugins that use SCIPcopy()
6003- fixed bug in DINS w.r.t. column generation
6004- fixed bug in var.c where a possible multiaggregation was resolved to an aggregation but the variables types were not
6005 checked to prefer more general types for aggregating; possible memory loss removed
6006- fixed bug in prop_vbounds.c w.r.t. infinity lower and upper bound of variable bound variables
6007- fixed bug w.r.t. setting wall clocks
6008- fixed wrong assert in var.c (replaced `==` through SCIPsetIsEQ()), real values do not have to be exactly the same when
6009 computed in different function
6010- fixed bug in SCIPsolveIsStopped() where it could happen that TRUE was reported if a nodelimit was reached but
6011 checknodelimits had been set to FALSE
6012- fixed three bugs when writing in fzn format (wrongly splitted writing buffer, wrong variables was used, floats were printed to short)
6013- fixed bug in conflict.c, infeasibility analysis with big values led to wrong result
6014
6015- Heuristics:
6016 - fixed bug in DINS heuristic that occured when the incumbent solution value is outside the variable's current domain
6017 - fixed behavior of LNS heuristics when the subproblem aborts: continue in optimized mode, stop in debug mode
6018 - fixed segmentation fault in heur_subnlp.c which occured if resolving the NLP with a tighter feasibility tolerance
6019 failed with a solver error
6020 - fixed bug in heur_subnlp.c where constraints forbidding variable fixations where added if a cutoff was used in the subproblem
6021 - fixed bug in heur_subnlp.c where wrong constraints forbidding variable fixations where added in case of general integers
6022
6023- NLP:
6024 - fixed bug in changing quadratic coefficients of a row in the NLP
6025 - fixed various small bugs in nonlinear expressions code
6026 - fixed removal of fixed linear variables from a nonlinear row: a fixed variable may have not been removed if there was
6027 also a multiaggregated variable
6028
6029- LP:
6030 - implemented SCIPlpiGetPrimalRay() in SoPlex interface that has become available with SoPlex version 1.5.0.2
6031 - fixed two bugs at nodes with unbounded LP relaxation: don't check lp rows of infinite solution; don't analyze conflict
6032 due to primal cutoff bound of -infinity
6033 - fixed wrong assumption that an optimal LP solution in the root is optimal for the problem if there are no active
6034 pricers, need to check also whether all variables are in the LP
6035
6036- Constraints:
6037 - fixed bug in reader_cip regarding reading of very long constraints
6038 - fixed bug while after restarting possible the aggregted variables were not removed in setppc constraints
6039 - fixed bug in cons_knapsack: in seldom circumstances the relaxation of a linear constraint can detect infeasibility,
6040 which was not handled properly
6041 - fixed bug w.r.t. to pricing variables in case new initial constraints come in during the price and cut loop
6042 - fixed bug in cons_soc.c w.r.t. upgrading from quadratic constraints with finite left-hand-side
6043 - fixed bug caused by not (correctly) counting boundchanges in cons_varbound.c
6044 - fixed bug in sorting mechanism in cons_xor.c
6045 - fixed wrong (neg)cliquepartition check in cons_knapsack.c when deleting a coefficient
6046 - fixed bug in cons_quadratic: in seldom cases, fixed variables may have been substituted out wrongly in presolve
6047 - fixed bugs in cons_countsols.c w.r.t. collecting feasible solutions and forbidding a found solution
6048 - fixed bug in cons_linear.c: multiaggregated variables were not removed when adding during solve, leading to a failing
6049 assert in tightenBounds due to an unsuccessful bound tightening
6050
6051- Memory:
6052 - fixed bug concerning overflow in memsize calculation in set.c
6053 - fixed memory leak in SoPlex LP interface when requesting an unbounded solution
6054 - fixed memory leak in SoPlex LP interface when solving with LP scaling
6055 - fixed memory leaks in reader of TSP example
6056
6057@section RN201 SCIP 2.0.1
6058*************************
6059
6060Performance improvements
6061------------------------
6062
6063- SCIP with SoPlex as LP solver now uses auto pricing by default (start with devex, switch to steepest
6064 edge after some iterations); this fixes timeouts on instances where devex converges very slowly
6065- fixing lifting of new knapsack items which are negated items of already included items, this could lead to very long presolving
6066- fixed performance issue in presolving w.r.t. to computing the number of new fixings, aggregated,
6067 and so on before a constraint handler presolver is called
6068- in case of adding constraints during pricing with initial flag set to
6069 TRUE, we add now these constraints after the pricing round to the LP
6070- changed parameter values in clique separator in order to avoid very large branch-and-bound trees
6071
6072Interface changes
6073-----------------
6074
6075### New and changed callbacks
6076
6077- allow access of transformed constraints in `SCIP_STAGE_TRANSFORMED`
6078
6079### Changed parameters
6080
6081- replaced parameter `constraints/quadratic/minefficacy` by `constraints/quadratic/minefficacysepa` and `constraints/quadratic/minefficacyenfo`
6082- added possible values `a` and `e` for `constraints/soc/nlpform` to enable automatic choice and convex exponential-sqrt
6083 form for SOC constraint representation in NLP
6084
6085Fixed bugs
6086----------
6087
6088- fixed bug w.r.t. looseobjval; the counting of number of loose variables in the LP data structure was incorrect in case
6089 a variable got aggregated or multi-aggregated
6090- fixed bug in copy method of objvardata which should only create a new `SCIP_VARDATA` if the implemented subclass create
6091 a copy of the given objvardata object
6092- fixed bug in lp.c where in case of objlimit reached and fastmip not all variables where priced because of an incorrect
6093 dual solution
6094- fixed bugs in binpacking example w.r.t. empty struct and not initializing an array
6095- fixed bugs in sepa_clique.c concerning incorrect way to ignore implicit binary variables in cliques and non-active
6096 variables in implications
6097- fixed some bugs w.r.t. to casting pointer arrays
6098- fixed bug in vars.c which handled arrays with parts of original variables during resolving to active variables (using
6099 SCIPvarsGetProbvarBinary) wrong
6100- fixed bug in nlp.c: nlrowSearchQuadElem was using SCIPquadelemSortedFind() incorrectly
6101
6102- Branching:
6103 - fixed assertion w.r.t. to probing during the propagation round of a branch-and-bound node
6104 - fixed computation of node's objective value estimate when branching on continuous variables (see
6105 SCIPtreeCalcChildEstimate(), SCIPtreeBranchVar())
6106 - fixed bug in statistic w.r.t. number of calls for external branching candidates
6107 - fixes to branching on continuous variables
6108
6109- Reader:
6110 - fixed bug in reader_gms.c: linear coefficients for quadratic variables were not printed if they had no
6111 square-coefficient
6112 - fixed bug in reader_mps: indicator constraints do not output the slack variables anymore
6113
6114- Constraints:
6115 - fixed bugs in SCIPcopyConss: copy all active constraints (including disabled ones), *valid was not initialized to TRUE
6116 - fixed bug in debug.c w.r.t. checking of constraints and continuous variables
6117 - fixed bug in cons.c which didn't allow the changing of the separation and enforcement flag of a constraint in the
6118 problem stage
6119 - corrected behavior of the copy function in cons_indicator.c: create artificial linear constraint if linear constraint
6120 was deleted
6121 - fixed bug in cons_indicator.c: presolving cannot delete linear constraints; several other minor bugfixes
6122 - fixed bugs in cons_bounddisjunction where the branching during the constraint enforcement was done incorrectly
6123 - fixed bugs in cons_orbitope.c: orbitopal fixing for the packing case had two bugs; also fixed one wrong assert
6124 - fixed bugs in cons_sos?.c: take average of objestimate
6125 - fixed bug in cons_logicor, implications on none `SCIP_VARTYPE_BINARY` variable were handled wrong
6126 - fixed bug in cons_linear while trying to add a conflict without any variables
6127 - fixed bug in cons_indicator.c: creating constraints in transformed stage is now possible
6128
6129- LP Interface:
6130 - fixed bug w.r.t. memory allocation for all values of a column in lpi_cpx.c
6131 - fixed bugs in SCIPnlpiOracleChgLinearCoefs() and SCIPnlpiOracleChgQuadCoefs() for the case where new coefficients where
6132 added
6133 - fixed bugs in lpi_none.c w.r.t. debug and opt mode
6134 - fixed bug in lpi_cpx.c w.r.t. to wrong handling in case the crossover did not succeed
6135
6136- Heuristics:
6137 - fixed bug in heur_subnlp when initialized starting values of a fixed variable in the NLP of the subscip
6138 - fixed bug in heur_undercover: removed option globalbounds, since we are not allowed to relax bounds at a probing node
6139 - fixed bug in heur_shiftandpropagate where some variables were initialized too late
6140 - fixed numerical issue in some heuristics: nearly-integral values that are between the feasibility and the integrality
6141 tolerance might not have been rounded correctly
6142 - fixed bug in heur_guideddiving: best solution is now copied to avoid deletion in case of many new solutions
6143 - fixed bug in DINS heuristic, information storage for binary variables could lead to bad memory access in column
6144 generation applications
6145 - fixed bug in heur_shiftandpropagate.c: Now, the heuristic checks rows for global infeasibility at the beginning. This
6146 check is only relevant if presolving is disabled.
6147 - fixed bug in heur_subnlp when forbidding a particular combination of integer variables in the main problem
6148
6149@section RN200 SCIP 2.0.0
6150*************************
6151
6152Features
6153--------
6154
6155- added relaxation structure to SCIP, it represents global relaxation information independent from a specific relaxator;
6156 at the moment, it contains information about the relaxation solution stored in the variables: objective value and
6157 validness
6158- SCIP may now be manually restarted
6159- SCIPsolveKnapsackExactly() got a new 12. parameter `SCIP_Bool* success` which stores if an error occured during
6160 solving(normally a memory problem)
6161- SCIP can now handle problems with continuous variables w.r.t. to counting (the projection to the integral variables
6162 are counted)
6163- an XML-parser is available in the src/xml subdirectory
6164- We do not distinguish between block memory for the original and the transformed problem anymore. The same
6165 block memory is now used in both problem stages.
6166- added new sorting method SCIPsortLongPtr(), SCIPsortDownLongPtr() and all corresponding methods
6167- added new sorting method SCIPsortRealIntPtr(), SCIPsortDownRealIntPtr() and all corresponding methods
6168
6169- Heuristics:
6170 - SCIP can now copy instances (e.g. for heuristics)
6171 - new undercover heuristic for MINLPs: fixes variables such as to obtain a linear or convex subproblem and solves this
6172 - primal heuristics may now already be called before presolving, using the new timing point
6173 `SCIP_HEURTIMING_BEFOREPRESOL`. Note that solutions that are added before/during presolving, will be retransformed to
6174 the original space.
6175 - primal heuristics may now be called during presolving, using the new timing point `SCIP_HEURTIMING_DURINGPRESOLLOOP`
6176 - added heuristic zirounding (heur_zirounding.{c,h})
6177 - added heuristic twoopt (heur_twoopt.{c,h})
6178 - added new NLP heuristic (heur_subnlp.{c,h}) which solves the sub-NLP that is obtained by fixing all discrete variables
6179 in the CIP and applying SCIP's presolving
6180 - feasibility pump heuristic now implements all functionality for feasibility pump 2.0
6181
6182- Reader:
6183 - can now read XML-solution files as used by CPLEX
6184 - the MPS reader can now read MIQPs and MIQCPs where a quadratic objective function can be specified by a QMATRIX or
6185 QUADOBJ section and the quadratic part of a quadratic constraint by a QCMATRIX
6186 - the MPS reader can now write quadratic and SOC constraints
6187 - the GAMS reader can now write SOC constraints
6188 - added support for bool_gt, bool_lt, bool_ge, bool_le, bool_ne, bool_not, int_times, int_minus, int_plus, int_negate,
6189 float_times, float_minus, float_plus, float_negate constraints to flatzinc reader
6190 - the LP reader (.lp files) can now read MIQPs and MIQCPs and write quadratic and SOC constraints
6191 - the LP reader (.lp files) and MPS reader can now read semicontinuous variables, they are handled by creating bound
6192 disjunction constraints
6193 - added new reader for polynomial mixed-integer programs (reader_pip.{c,h}) as used in the POLIP
6194
6195- Indicator constraints:
6196 - SCIP can now handle indicator constraints (reading (from LP, ZIMPL), writing, solving, ...) see \ref cons_indicator.h.
6197 - the indicator constraint can now decompose the problem, i.e., not add the linear constraint to the problem if all of
6198 its variables are continuous
6199 - can now read and write indicator constraints in the (extended) MPS format
6200 - cons_indicator tries to adapt solutions to get feasible during check
6201 - cons_indicator allows to store information on other linear constraints that might help to separate cuts
6202
6203- Constraint handlers:
6204 - Solution counting extended to constraint integer programs, this also
6205 includes constraint integer programs which contain continuous variables
6206 - The solution behavior of SCIP can be diversified by randomly permuting constraints and variables or randomly
6207 determining a set of branching variables with a unique high priority
6208 - `negated cliques` (1<=i<=n : sum (x_i) >= n-1) were added and we are using them now inside the knapsack constraint
6209 handler, the cliquepartitioning which is returned by SCIPcalcCliquePartition() contains now integer != 0, negatives ones
6210 indicates a negated clique and positive ones indicates a normal clique
6211 - SCIP is now able to detect in DEBUG-mode whether a constraint or variables which will be added, was also created in
6212 the same scip instance, if not an error is thrown
6213 - cons_knapsack is now able to detect negated cliques due to negated cliques on knapsack constraints
6214 - SCIP is now able to write non-linear opb-files(linear instances with and-constraints)
6215 - New constraint handlers for linking constraints (only Beta), cumulative constraints, and for breaking orbitopal symmetries
6216 - `negated cliques` handling in knapsack constraint handler got changed due to the new method
6217 SCIPcalcNegatedCliquePartition() resulting in new consdata members `negcliquepartition`, `negcliquepartitioned` and
6218 `nnegcliques`; changed SCIPcalcCliquePartition() so all cliquepartitions (calculated by SCIPcalcCliquePartition() or
6219 SCIPcalcNegatedCliquePartition(), which uses the first one) contain again not negative integers
6220 - `and`, `knapsack`, `linear`, `logic`, `or`, `quadratic`, `setpp`, `varbound`, `xor` and `clique` constraint handlers
6221 can handle implicit binary variables
6222 - knapsack constraint handler is now able to pairwise presolving constraints
6223 - constraint handlers `logicor`, `and`, `or` can parse their output
6224 - constraint handler `or` can copy its constraints
6225 - added packing/partitioning orbitope constraint handler for symmetry handling (cons_orbitope.{c,h})
6226 - added constraint handler for second order cone constraints (cons_soc.(c|h))
6227 - added constraint handler cons_linking.{c,h} (see cons_linking.c for more details)
6228 - cons_quadratic can make solutions in CONSCHECK feasible for the quadratic constraints by moving values of linear
6229 variables and passing the modified solution to the trysol heuristic
6230 - constraint handler can now register their upgrade functions for quadratic constraints to cons_quadratic (similar to
6231 LINCONSUPGD)
6232
6233- Separation:
6234 - New separators for oddcycle cuts and Chvatal-Gomory cuts using sub-MIPs
6235 - modified implementation of separation algorithms in cons_knapsack.c according to results of diploma thesis; including
6236 super-additive lifting (disabled)
6237 - uncommented decomposeProblem() in sepa_zerohalf.c (in default settings, not used anyway): was not adapted to the case
6238 that contiuous variables are allowed in a row
6239 - new separator rapid learning (sepa_rapidlearning.{c,h}) that produces conflicts, global bound changes, primal
6240 solutions and initializes inference values for branching
6241 - added Chvatal-Gomory cuts separated with a sub-MIP (sepa_cgmip.{c|h})
6242 - added reader for 'Weigted Boolean Optimization': problems (reader_wbo.{c,h}), this reader needs the reader_opb files
6243 - new separator oddcycle (sepa_oddcycle.{c,h}) separates oddcycle inequalities using the implication/conflict graph and
6244 dijkstra-algorithm based on binary heaps (dijkstra/dijkstra_bh.{c,h})
6245
6246- Branching:
6247 - Branching on externally given candidates, the \ref BRANCH 'branching rules' have a second new callback method
6248 (see type_branch.h for more details): SCIP_DECL_BRANCHEXECEXT(x) can be used to branch on external branching candidates,
6249 which can be added by a user's `relaxation handler` or `constraint handler` plugin, calling SCIPaddExternBranchCand().
6250 - added branchcands for relaxator solution, that can be added by the relaxator and used by branching rules
6251 - added relaxsol to variables, s.t. a relaxator can store a solution on which branching or separation can be done
6252 - SCIP can now branch on relaxation solutions that are either installed to the relaxsol field of the variables or added
6253 to the list of relaxation candidates, e.g., by constraint handlers. Branching on relaxation solutions is performed if
6254 the enforcement resulted in an unresolved infeasibility and there are no LP branching candidates, but before pseudo
6255 solution branching. The branching rules leastinf, mostinf, random and pscost implement the callback for branching on
6256 relaxation candidates.
6257 - SCIP can branch on continuous variables. The branching value x' must not be one of the bounds. Two children (x <= x',
6258 x >= x') will be created.
6259 - the vbc visualization adds the branching type (lower or upper bound change) and the new bound to the node information
6260 - the vbc visualization adds the new bound of the branched variable to the node information
6261
6262- Statistic:
6263 - added statistic information about the first primal solution to SCIP statistic; in the statistic output a new line
6264 appears with this information
6265 - now the statistic displays the number of calls of the feasibility checking method of each constraint handler and the
6266 running time of it
6267
6268- Propagation:
6269 - New rounding and propagation heuristics
6270 - New propagator for variable bounds
6271 - primal heuristics may now be called directly after the node's propagation loop, using the new timing point
6272 `SCIP_HEURTIMING_AFTERPROPLOOP`
6273 - following methods SCIPinferVarUbProp(), SCIPinferVarLbProp(), SCIPinferVarLbCons(), SCIPinferVarUbCons() have a new 6th
6274 parameter `SCIP_Bool force` which allows bound tightening even if the difference to the newbound is below bound
6275 strengthening tolerance
6276 - added propagator for variable lower and upper bounds (prop_vbounds.{c,h}); adjusted cons_varbound.c, var.c, and,
6277 implics.c to work correctly with the new propagator
6278
6279- Nonlinear CIPs:
6280 + Improved constraint handler for quadratic constraints
6281 + New constraint handler for second order cone constraints
6282 + New MINLP heuristics (undercover, subnlp)
6283 + Preliminary support for non-linear relaxations (via expression trees)
6284 + Automatic branching on solutions from arbitrary relaxations and on continuous variables
6285
6286Performance improvements
6287------------------------
6288
6289- improved `settings/emphasis/cpsolver.set` to decrease time per node
6290- reworked access to pseudo solution and inference value of variables in order to reduce function calls
6291- changed default value of parameter `nodeselection/restartdfs/selectbestfreq` to 0; this means if the current node has
6292 no children the node with the best bound is selected (SCIPgetBestboundNode())
6293- added a dual reduction step in cons_knapsack.c
6294- fasten check for common cliques in SCIPcliquelistsHaveCommonClique
6295- SCIP with CPLEX as LP solver now uses quickstart steepest edge pricing as default instead of steepest edge pricing
6296- avoid unnecessary domain propagation and LP resolve at nodes with infeasible LP relaxation
6297- improved zerohalf cut separator: more than one delta is tested for MIR cuts, better handling of dense base
6298 inequalities, faster scaling of fractional coefficients in rows (now enabled), improved parameter settings (presolving)
6299
6300- LP solution:
6301 - in root node, first LP solution is checked for feasibility to avoid expensive setup
6302 - avoided restarting if LP solution is feasible
6303 - separators are not called any longer for an integral initial LP solution
6304
6305Examples and applications
6306-------------------------
6307
6308- New branch-and-price example which includes Ryan/Foster branching (binpacking example)
6309- New example illustrating the use of an event handler (`example/Eventhdlr`)
6310
6311Interface changes
6312-----------------
6313
6314- Enhanced user interface for callable library: manual restarts, predefined settings and many other features
6315- Support of wbo format for weighted PBO problems, IBM's xml-solution format and pip format for polynomial mixed-integer programs
6316- Extended reader for Flatzinc models
6317- new API for 'expressions interpreter': code that evaluates expression trees, including first and second derivatives
6318- NLP solver interface (NLPI) now independent of SCIP like LPI
6319- SCIP can now maintain a central NLP relaxation of the problem (similar to LP)
6320- SCIP can now manage a list of external codes (e.g., LP or NLP solver, ZIMPL)
6321- lp.h/lp.c and the lpi's were changed according to the changes mentioned below.
6322- adding and deletion of rows to the separation storage and to the LP can now be catched by events
6323 (`SCIP_EVENTTYPE_ROWADDEDSEPA`, `SCIP_EVENTTYPE_ROWDELETEDSEPA`, `SCIP_EVENTTYPE_ROWADDEDLP`, `SCIP_EVENTTYPE_ROWDELETEDLP`)
6324
6325### New and changed callbacks
6326
6327- new callback SCIP_DECL_BRANCHEXECRELAX(), together with new parameter in SCIPincludeBranchrule() for branching on a
6328 relaxation solution
6329
6330- Copying a SCIP instance:
6331 - Constraint handlers have two new callback methods. One for copying the constraint handler plugins
6332 SCIP_DECL_CONSHDLRCOPY() and the other for copying a constraint itself, SCIP_DECL_CONSCOPY().
6333 - All plugins, like \ref BRANCH `branching rules` and \ref HEUR `primal heuristics`, have a new callback method (see, e.g.,
6334 type_branch.h and type_heur.h for more details):
6335 - SCIP_DECL_BRANCHCOPY(x), SCIP_DECL_HEURCOPY(x) etc.
6336 - When copying a SCIP instance, these methods are called to copy the plugins.
6337 - The main problem has a new callback method (see type_prob.h for more details) SCIP_DECL_PROBCOPY(x) when copying a
6338 SCIP instance, this method is called to copy the problem's data.
6339 - Variables have a new callback method (see type_var.h for more details) SCIP_DECL_VARCOPY(x) when copying a SCIP
6340 instance, this method is called to copy the variables' data.
6341
6342- Restarts:
6343 - The callback SCIP_DECL_PROBEXITSOL(x) in the main problem has one new parameter (see type_prob.h for more details):
6344 - The parameter `restart` is `TRUE` if the callback method was triggered by a restart.
6345
6346### Deleted and changed API methods
6347
6348- All C++ objects and constructors have a SCIP pointer, now.
6349- added parameter scip to ObjCloneable::clone()
6350- changes in a row can now be catched via row events (SCIPcatchRowEvent(), SCIPdropRowEvent(),
6351 `SCIP_EVENTTYPE_ROWCOEFCHANGED`, `SCIP_EVENTTYPE_ROWCONSTCHANGED`, `SCIP_EVENTTYPE_ROWSIDECHANGED`)
6352- added new parameter `varcopy` to SCIPcreateVar() to add the function for copying variable data
6353- in case of using SCIPwriteTransProblem() the currently (locally) valid problem is written this now also includes the
6354 local constraints
6355
6356- Settings:
6357 - The predefined setting files like `settings/cuts/off.set,aggressive.set,fast.set` have been replaced by
6358 interface methods like SCIPsetHeuristics(), SCIPsetPresolving(), SCIPsetSeparating(), and SCIPsetEmphasis() in
6359 \ref scip.h and by user dialogs in the interactive shell like
6360 `SCIP> set {heuristics|presolving|separating} emphasis {aggressive|fast|off}` or
6361 `SCIP> set emphasis {counter|cpsolver|easycip|feasibility|hardlp|optimality}`
6362 - All functions for setting user parameters of different types like SCIPparamSetBool(), SCIPparamSetChar(),
6363 SCIPparamSetInt(), SCIPparamSetLongint(), and SCIPparamSetString() in pub_paramset.h have a new parameter
6364 `quiet` it prevents any output during the assign to a new value.
6365
6366- NLP:
6367 - NLPIs can now be used without generating a SCIP instance (i.e., do not require a SCIP pointer), code moved into src/nlpi
6368 - NLPIs can now be managed like other SCIP plugins, i.e., they can be included into the SCIP core and accessed by
6369 methods SCIPincludeNlpi(), SCIPfindNlpi(), SCIPgetNNlpis(), SCIPgetNlpis(), SCIPsetNlpiPriority()
6370
6371- Intervalarithmetic:
6372 - method SCIPgetVarPseudocostCurrentRun() now returns the pseudocost value of one branching direction, scaled to a unit
6373 interval, old method now called SCIPgetVarPseudocostValCurrentRun()
6374 - renamed SCIPintervalScalarProductRealsIntervals()/SCIPintervalScalarProduct() by
6375 SCIPintervalScalprodScalars()/SCIPintervalScalprod() and redesigned them in intervalarith.c including new methods
6376 SCIPintervalScalprodScalarsInf/Sup()
6377
6378- Branching:
6379 - The usage of strong branching changed. Now, SCIPstartStrongbranch() and SCIPendStrongbranch() must be
6380 called before and after strong branching, respectively.
6381 - The methods SCIPgetVarPseudocost() and SCIPgetVarPseudocostCurrentRun() in \ref scip.h now return the pseudocost value of
6382 one branching direction, scaled to a unit interval. The former versions of SCIPgetVarPseudocost() and
6383 SCIPgetVarPseudocostCurrentRun() are now called SCIPgetVarPseudocostVal() and SCIPgetVarPseudocostValCurrentRun(), respectively.
6384 - The methods SCIPgetVarConflictScore() and SCIPgetVarConflictScoreCurrentRun() in \ref scip.h are now called
6385 SCIPgetVarVSIDS() and SCIPgetVarVSIDSCurrentRun(), respectively.
6386 - The methods SCIPvarGetNInferences(), SCIPvarGetNInferencesCurrentRun(), SCIPvarGetNCutoffs(), and
6387 SCIPvarGetNCutoffsCurrentRun() are now called SCIPvarGetInferenceSum(), SCIPvarGetInferenceSumCurrentRun(),
6388 SCIPvarGetCutoffSum(), and SCIPvarGetCutoffSumCurrentRun(), respectively. Furthermore, they now return
6389 `SCIP_Real` instead of `SCIP_Longint` values.
6390 - The method SCIPgetVarStrongbranch() has been replaced by two methods SCIPgetVarStrongbranchFrac() and
6391 SCIPgetVarStrongbranchInt().
6392
6393- Copying a SCIP instance:
6394 - Every new callback method resulted in a new parameter of the include function for the corresponding plugin,
6395 e.g., SCIPincludeBranchrule() has two new parameters `SCIP_DECL_BRANCHCOPY((*branchcopy))` and
6396 `SCIP_DECL_BRANCHEXECREL((*branchexecrel))`. In the same fashion, the new callbacks
6397 `SCIP_DECL_VARCOPY` and `SCIP_DECL_PROBCOPY` led to new parameters in SCIPcreateVar() and SCIPcreateProb() in
6398 scip.c, respectively.
6399 - W.r.t. to copy and the C++ wrapper classes there are two new classes. These are `ObjCloneable` and `ObjProbCloneable`.
6400 The constraint handlers and variables pricers are derived from `ObjProbCloneable` and all other plugin are derived from `ObjCloneable`.
6401 Both classes implement the function `iscloneable()` which return whether a plugin is clone able or not. Besides that each class has a
6402 function named `clone()` which differ in their signature. See objcloneable.h, objprobcloneable.h, and the TSP example for more details.
6403 - SCIPincludeHeur() and SCIPincludeSepa() in \ref scip.h, as well as scip::ObjSepa() and scip::ObjHeur(), have a new parameter:
6404 `usessubscip`: It can be used to inform SCIP that the heuristic/separator to be included uses a secondary SCIP instance.
6405 - The argument success in `SCIP_DECL_CONSCOPY` has been renamed to valid.
6406
6407- Heuristics:
6408 - SCIPcutGenerationHeuristicCmir() in sepa_cmir.h has three new parameters:
6409 - `maxmksetcoefs`: If the mixed knapsack constraint obtained after aggregating LP rows contains more
6410 than `maxmksetcoefs` nonzero coefficients the generation of the c-MIR cut is aborted.
6411 - `delta`: It can be used to obtain the scaling factor which leads to the best c-MIR cut found within
6412 the cut generation heuristic. If a `NULL` pointer is passed, the corresponding c-MIR cut will already be
6413 added to SCIP by SCIPcutGenerationHeuristicCmir(). Otherwise, the user can generate the cut and add it to SCIP
6414 on demand afterwards.
6415 - `deltavalid`: In case, the user wants to know the best scaling factor, i.e., `delta` passed is not `NULL`,
6416 `deltavalid` will be `TRUE` if the stored scaling factor `delta` will lead to a violated c-MIR cut.
6417
6418### New API functions
6419
6420- added SCIPcalcNegatedCliquePartition() to scip.c to calculate a clique partition on negations of all given binary
6421 variables
6422- SCIPpermuteArray() that randomly shuffles an array using the Fisher-Yates algorithm
6423- SCIPgetRandomSubset() that draws a random subset of disjoint elements from a given set of disjoint elements
6424- SCIPswapPointers()
6425- SCIPlpiGetSolverDesc() to get a descriptive string of an LP solver (developer, webpage, ...)
6426- SCIPholelistGetNext() to get the next hole of the hole list
6427- SCIPlpRecalculateObjSqrNorm() which is used when the old calculated square norm was unreliable
6428- SCIPpricerIsDelayed() which returns if the pricer is delayed (see pub_pricer.h)
6429
6430- Variables:
6431 - SCIPvarIsBinary() which checks if a variable is (implicit) binary (see var.c for more details)
6432 - SCIPvarGetHolelistOriginal(), SCIPvarGetHolelistGlobal(), SCIPvarGetHolelistLocal() to get the original, global and local holes, respectively
6433 - SCIPvarGetProbvarHole() to tranform a given domain hole to the corresponding active, fixed, or multi-aggregated variable
6434
6435- Restart:
6436 - allow user to trigger a restart during presolving SCIPrestartSolve()
6437 - SCIPrestartSolve() that allows the user to manually restart the solving process
6438 - SCIPisInRestart() to detect whether we are currently restarting
6439
6440- Heuristics:
6441 - for heuristics SCIPheurSetFreq() to change the frequency of the heuristic (pub_heur.h, heur.c)
6442 - SCIPsepaUsesSubscip(), SCIPheurUsesSubscip()
6443
6444- Intervalarithmetic:
6445 - SCIPeventGetHoleLeft() and SCIPeventGetHoleRight() for accessing the left right interval bound of a domain hole added or removed event
6446 - SCIPholelistGetLeft() and SCIPholelistGetRight()to get the left and right interval bounds of the open hole interval
6447 - SCIPintervalAddInf/Sup/Vectors(), SCIPintervalMulInf/Sup() in intervalarith.c
6448
6449- Sorting:
6450 - added SCIPsortPtrPtrLongIntInt(), SCIPsortLongPtrPtrIntInt() and corresponding sorting/inserting/deleting methods in
6451 pub_misc.h and necessary defines in misc.c
6452 - added SCIPsortLongPtrInt() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
6453 - added SCIPsortPtrPtrInt() (and various other) and corresponding sorting/inserting/deleting methods in pub_misc.h and
6454 necessary defines in misc.c
6455 - SCIPsortPtrBool() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
6456
6457- Constraint Handlers:
6458 - SCIPconshdlrGetEnfoConss(), SCIPconshdlrGetNEnfoConss()
6459 - can now forbid upgrading of individual linear constraints (SCIPmarkDoNotUpgradeConsLinear())
6460 - SCIPpermuteProb() that randomly permutes constraints and variables
6461 - SCIPgetResultantOr() which returns the resultant of an `or` constraint
6462 - SCIPmarkDoNotUpgradeConsLinear() in cons_linear.?, which allows to forbid upgrading of linear constraints
6463 - SCIPgetNUpgrConss() which returns the number of upgraded constraints
6464 - SCIPconshdlrGetCheckTime() and SCIPconshdlrGetNCheckCalls() which returns the running time in the feasibility checking of the
6465 corresponding constraint handler respectively the number of calls of the checking method (implemented in cons.c)
6466
6467- Copy:
6468 - SCIPcopy() to clone a SCIP instance
6469 - SCIPcopyPlugins(), SCIPcopyParamSettings(), SCIPcopyVars(), SCIPcopyConss(), SCIPgetVarCopy() to copy
6470 individual parts of a SCIP instance separately.
6471 - SCIPcopyProbData() and SCIPprobCopyProbData() which copies the probdata from a sourcescip to a targetscip
6472
6473- Branching:
6474 - two new functions SCIPgetVarsStrongbranchesFrac()/SCIPgetVarsStrongbranchesInt() for computing strong branching
6475 information for several variables
6476 - SCIPbranchruleGetNRelaxCalls() to get the total number of times, a particular branching rule was called on a relaxation solutions
6477 - SCIPbranchRelax() to branch on a relaxation solution
6478 - SCIPbranchVarVal() to branch on an arbitrary value within the variable's bounds
6479 - SCIPbranchGetBranchingPoint() and SCIPgetBranchingPoint() to select branching point for a variable, e.g.,
6480 ensure branching point is inside the interval for a continuous variable
6481 - SCIPexecRelpscostBranching() in branch_relpscost.{c,h}; this method allows of calling the reliability
6482 pseudo cost branching algorithm for given set of branching candidates from the outside
6483 - SCIPinitVarBranchStats() to initialize the branching statistics (such as pseudo costs, VSIDS, inference values) of a variable
6484 - SCIPselectBranchVarPscost() in branch_pscost.{c,h}; this method selects from a given candidate array a
6485 branching variable w.r.t. pseudo cost branching for relax candidates
6486
6487- Reading, Writing and Parsing:
6488 - SCIPparseVarName() which parses a string in cip-format as a variable name
6489 - SCIPparseVarList() which parses a string as a variable list in cip-format
6490 - the Flatzinc reader can now handle the output annotations of the Flatzinc format; the method SCIPprintSolReaderFzn()
6491 outputs the given solution in Flatzinc format w.r.t. the output annotations
6492 - SCIPprintSolReaderFzn() which prints the best solution in Flatzinc format w.r.t. to the output annotations
6493 in the input file of the flatzinc model
6494 - SCIPwriteVarName() which writes a variable in cip-format to given stream
6495 - SCIPwriteVarsList() which writes an array of variables in cip-Format to given stream
6496 - SCIPwriteVarsLinearsum() which writes an array of variables and coefficients as linear sum in cip-Format to given stream
6497
6498- Copying a SCIP instance:
6499 - SCIPapplyRens() in \ref heur_rens.h has a new parameter `uselprows`. It can be used to switch from LP rows
6500 to SCIP constraints as basis of the sub-SCIP constructed in the RENS heuristic.
6501
6502- Parameters:
6503 - SCIPsetParamsCountsols() which sets the parameter for a valid counting process
6504 - SCIPsetEmphasis() which sets parameter to detect feasibility fast, handle hard LP, solves easy CIPs fast, behaves like a
6505 CP solver, set parameter for a valid counting process; the desired behavior is triggered via a parameter of the function
6506 - SCIPresetParam() to reset the value of a single parameter to its default value
6507
6508- Settings:
6509 - added SCIPsortRealRealRealPtr() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
6510 as basis for the subSCIP, setting ist to TRUE (uses LP rows) will lead to same version as before
6511 - SCIPsetHeuristics(), SCIPsetSeparating(), SCIPsetPresolving() which set the heuristics to aggressive, fast, off, or
6512 default settings, depending on the `SCIP_PARAMSET` parameter
6513 - SCIPsetSubscipsOff() which disables all plugins that uses subscips
6514 - SCIPsepaSetFreq() to set the calling frequency of a separator
6515
6516### Command line interface
6517
6518- added new dialog for setting the SCIP parameters for hardlp, optimality, easy CIP, CP like search
6519- added new dialog for setting the SCIP parameters for feasibility problems `SCIP> set emphasis feasibility`
6520- added new dialog for setting the SCIP parameters for counting `SCIP> set emphasis counting`
6521- added new dialog for setting presolving to aggressive, fast, or off in interactive shell
6522- added new dialog for setting separation to aggressive, fast, or off in interactive shell
6523- added new dialog for writing all solutions which are collected during the counting process (see cons_countsols.{c,h})
6524- added new dialog for setting heuristics to aggressive, fast, or off in interactive shell
6525- added new dialog `display pricers` which displays all included pricers
6526
6527### Interfaces to external software
6528
6529- added interface to CppAD (nlpi/exprinterpret_cppad.cpp)
6530- Improved Xpress, CPLEX, SoPlex interfaces
6531- the SoPlex interface now includes equilibrium scaling on lp's solved from scratch without starting basis
6532- the SoPlex interface can now double check each SoPlex result against CPLEX (lpi_spx.cpp)
6533- the SoPlex interface has the option to restore basis only after entire strong branching phase instead of after each
6534 strong branch (off, because it mostly appears to increase strong branching time and iterations) (lpi_spx.cpp)
6535
6536### Changed parameters
6537
6538- removed parameter `constraints/knapsack/maxnumcardlift` and adapted setting files
6539- changed parameter `lp/fastmip` from boolean to integer, possible values are 0 (off), 1 (medium, default), 2 (full,
6540 must not be used with branch-and-price).
6541
6542### New parameters
6543
6544- `branching/clamp` to set the minimal fractional distance of a branching point to a continuous variable' bounds
6545- `branching/random/seed` to change the initial seed value of the branching rule random
6546- `constraints/indicator/addCouplingCons` that allows to add variable upper bounds if addCoupling is true
6547- `constraints/indicator/enforceCuts` that allows to check for violated cust in enforcement
6548- `constraints/indicator/maxCouplingValue` for the maximal value of the coefficient in a coupling inequality/constraint
6549- `constraints/indicator/noLinconsCon` which controls whether the linear constraint is not explicitly
6550 added to the problem. default is FALSE
6551- `constraints/knapsack/dualpresolving` to switch dualpresolving on/off inside the knapsack constraint handler, default is TRUE
6552- `constraints/knapsack/presolpairwise` that allows pairwise presolving of knapsack constraints, default is TRUE
6553- `constraints/knapsack/presolusehashing` that allows fast pairwise presolving of knapsack constraints, default is TRUE
6554- `heuristics/crossover/dontwaitatroot` that allows to call crossover at root node independently from nwaitingnodes
6555- `heuristics/rens/uselprows` that allows to switch between LP row and SCIP constraints as basis for the
6556 subSCIP, default is TRUE (uses LP rows)
6557- `lp/rowrepswitch` telling simplex solver to switch to row representation of the basis (if possible),
6558 if number of rows divided by number of columns exceeds this value (default value infinity, i.e. never switch)
6559- `lp/threads` to change the number of threads used to solve the LP relaxation (default is 0: automatic)
6560- `misc/lexdualstalling` that turns on the lex dual algorithm if the separation process is stalling
6561- `misc/usevartable` and `misc/useconstable` which turns on/off the usage of hashtables mapping from
6562 variable/constraint names to the variables/constraints; when turned off, SCIPfindVar() and SCIPfindCons() may not be
6563 used; the hashtables can be turned off for subMIPs to improve the performance, default value TRUE
6564- `misc/usesmalltables` which results in using smaller tables for names, cliques and cuts and improves
6565 the performace for smaller instances, default value FALSE
6566- `misc/permutationseed` to change the permutation seed value for permuting the problem after the
6567 problem is transformed (-1 means no permutation)
6568- `reading/zplreader/usestartsol` which allows to switch ZIMPL start solutions off, default value TRUE
6569- `vbc/dispsols` to propose if the nodes where solutions are found should be visualized in the branch and bound tree
6570
6571### Data structures
6572
6573- implemented the data structure and events for global and local domain holes added and removed
6574- new data structures and methods to handle nonlinear expressions in NLPI ({type_, struct_, pub_}expression.{h,c}):
6575 nlpioracle can store and evaluate general NLPs now, nlpi_ipopt can solve general NLPs now
6576
6577Testing
6578-------
6579
6580- minor changes on several evaluation scripts (new statuses: better, solved, sollimit, gaplimit) and short-mode for cmpres.awk
6581- support for FreeBSD (32- and 64-bit) including minor changes in several scripts in the check-directory
6582
6583Build system
6584------------
6585
6586### Makefile
6587
6588- added scripts check_*.sh, evalcheck_*.sh and check_*.awk for blis, glkp, gurobi and symphony (including targets in
6589 Makefile) and slightly modified scripts for cplex, cbc and mosek and cmpres-script
6590- added target `lintfiles` which allows to call flexelint with a list of file, for example, make lintfiles
6591 `FILES=src/scip/prop_vbounds.c`
6592- the NLP solver interfaces and expression interpreter are located in a separate library (libnlpi.*; similar to the lpi
6593 library) and is required to link against the SCIP library also projects that use SCIP via `make/make.project` need to
6594 change their Makefile (!!!): in the $(MAINFILE) target, add $(NLPILIBFILE) behind $(LPILIBFILE) in the dependencies
6595 and add $(LINKCXX_l)$(NLPILIB)$(LINKLIBSUFFIX) to the linker flags
6596- The additional NLPI library requires a change in the Makefile of SCIP's project:
6597 The $(MAINFILE) target now has $(NLPILIBFILE) as additional dependency and the linking
6598 command requires $(LINKCXX_l)$(NLPILIB)$(LINKLIBSUFFIX) as additional argument.
6599- A bug in the Makefiles of older versions of the SCIP examples may cause
6600 data loss. If you have a custom Makefile, please ensure that the target
6601 `clean` is changed as described here:
6602 http://scipopt.org/download/bugfixes/scip-1.2.0/make.txt.
6603
6604Fixed bugs
6605----------
6606
6607- fixed bug in conflict.c in the method conflictsetAddBound()
6608- fixed `bug` in projects Makefiles w.r.t. `make clean`
6609- fixed bug in rapid learning with wrong ordering of dual and primal bound update, primal bound is now updated inside
6610 rapid learning
6611- fixed potential bug in rapid learning with dual reductions
6612- fixed potential bug where SCIPselectSimpleValue() returns a value slightly outside of the given bounds due to rounding
6613 errors (probably cancelation in subtraction in SCIPfindSimpleRational), now use rounding control and check result
6614- fixed bug that SCIP could not be continued after it has been stopped due to a limit
6615- fixed bug in var.c: SCIPvarChgLbOriginal() and SCIPvarChgUbOriginal() cannot access original bounds if the variable is
6616 negated
6617- fixed potential bug with pseudo solution branching on free variables
6618- fixed bug with multiaggregations whose infimum and supremum are both infinite: in such a case multiaggregation is now
6619 forbidden
6620- fixed numerical issue with multiaggregations which are infinite in one direction: value of multiaggregated variable
6621 could have been larger then inifinity
6622- fixed bug w.r.t. of adding a variable bound variable to its self
6623- fixed bug concering the incorrect assumption that every solution computed in SCIPlpGetUnboundedSol() is integral (we
6624 will not branch but return `infeasible or unbounded` like in presolving)
6625- fixed bug while breaking an clique down to their impications (in SCIPcliquetableCleanup() in implics.c) where the
6626 variable was not of vartype `SCIP_VARTYPE_BINARY`, instead of adding an implication we add a variable bound
6627- fixed bug with debugging a solution: during restarts erroneously it was claimed that the primal solution is cut off
6628
6629- Interface:
6630 - fixed bug w.r.t. ObjDialog and displaying the description of the dialog
6631 - fixed bug when aborting pricing with Ctrl-C
6632
6633- LP:
6634 - fixed bug in scip.c w.r.t. to call of conflict analysis for LPs which reached the objective limit in case of diving
6635 - fixed bug with resolving LPs at infeasible root node
6636 - fixed bug in lp.c: in sumMIRRow() rowtoolong was not set correctly
6637 - fixed bug in lp.c w.r.t. objective limit reached and the chosen comparison (fixed buglist entry 40)
6638 - fixed bug in lp.c: if in SCIPlpSolveAndEval() the LP has to be solved from scratch due to numerical troubles, reset
6639 `SCIP_LPPARAM_FROMSCRATCH` to `FALSE` afterwards
6640 - fixed bug in lp.c SCIProwGetObjParallelism() due to a wrong parallelism value which arised from cancellations during
6641 calculation of squared euclidean norm of objective function vector of column variables
6642 - fixed bug in lp.c: SCIPlpGetUnboundedSol() did not ensure that unbounded solution lies withing the bounds of the
6643 variables
6644 - fixed bug in lp.c w.r.t. to the number of `active` pricer
6645
6646- Solve:
6647 - fixed bug in solve.c where relaxation branching candidates were cleared, but the relaxation was still marked solved
6648 and not called again, furthermore, adjusted criterions for solving a relaxation again
6649 - fixed bugs in solve.c: even with LP solving disabled, the root LP was solved in case continous variables are
6650 contained; setting pricing/maxvars(root) to 1 resulted in not calling the pricers
6651 - fixed bug in solve.c: make sure SCIP terminates correctly also when a user interrupt or gap limit is reached, i.e.,
6652 avoid error `pricing was aborted, but no branching could be created!`
6653
6654- Tree:
6655 - fixed bug in tree.c: if an explicit branching point is given, we may not recompute a better centering point
6656 - fixed bug in tree.c: propagate implications on multi-aggregated should not be performed
6657
6658- Constraints:
6659 - corrected several asserts in linear and quadratic constraint handler concerning parsing of CIP format
6660 - fixed bug while deleting redundant variables, which have no influence on changing the feasibility of the linear
6661 constraints, we need to update the sides of the constraint at each step, bug number 51 in bugzilla
6662 - fixed bug in copy procedure of AND constraint handler, negated variables have been copied to their originals
6663 - fixed bug when deleting a constraint where the update was delayed and not processed yet (in cons.c)
6664 - fixed bug in cons_linear.c: binary variables should not be multi-aggregated
6665 - fixed bug in cons_quadratic.c: curvature of bivariate quadratic constraints was not detected correctly
6666 - fixed bug in cons_sos2.c: the branching position was sometimes mistakenly increased
6667 - fixed bug in propagation of cons_sos2.c: the node can be cut off at more places: the previous version was not
6668 sucessfull in this respect
6669 - fixed bug in cons_linear.c:applyFixings() which could lead to lhs/rhs smaller/larger than -/+infinity
6670 - fixed bug in cons_linear.c in detectRedundantConstraints() and corrected old bug fix in SCIProwCreate(): we want lhs
6671 <= rhs to be satisfied without numerical tolerances in order to avoid numerical problems in the LP solver
6672
6673- Knapsack Constraint Handler:
6674 - fixed bug in cons_knapsack.c: mergeMultiples() now detects whether a node can be cut off
6675 - fixed bug in cons_knapsack.c w.r.t. to items with zero weight
6676 - fixed bug in cons_knapsack.c: In SCIPseparateRelaxedKnapsack() not all variables need to be active in deeper regions
6677 of the tree
6678 - fixed bug in cons_knapsack.c and sepa_clique.c: the assumption that implications are always nonredundant and contain
6679 only active variables is not correct anymore as the corresponing vbound might be missing because of numerics
6680
6681- Separation and Cuts:
6682 - fixed bug in cutpool.c: the hashkey computation was not constant over time
6683 - fixed bug in cutpool.c: hashkey of a row changed during the solving process (if a row is made integral after creation,
6684 maxabsval can be invalid when adding it to the pool, but might be recomputed later on)
6685 - fixed bug in sepa_rapidlearning.c, stop processing if there are no binary variables left
6686 - fixed bug in sepa_rapidlearning.c, corrected computation of right dualbound
6687 - fixed bugs in sepa_zerohalf.c, e.g., handling of intscaling and substitution of variable bounds
6688 - fixed bug in sepastore.c in sepastoreApplyLb/Ub being to hard on feasibility decisions
6689 - fixed bug in sepa_flowcover.c: numerical issues while computing candidate set for lambda
6690
6691- LP Interfaces:
6692 - fixed bug in SoPlex autopricing due to which autopricing had behaved like steepest edge pricing so far
6693 - fixed bug in lpi_clp.cpp: SCIPlpiChgBounds() checks if the column status exists in Clp before using it
6694 - fixed wrong assert in Cplex LPI: Due to numerical inaccuracies, a few pivots might be performed after refactorization
6695 - fixed bug concerning assert(!SCIPlpDivingObjChanged(lp)) which was caused by wrong infinity double parameters for
6696 cplex
6697 - fixed makefile system for `OSTYPE=darwin` w.r.t. to CPLEX as LP solver
6698
6699- Presolving:
6700 - fixed bug in cons_setppc: aggregated variables were not correctly removed in presolving
6701 - fixed bug in presolving of linear constraint handler: in redundancy detection, two different numerical epsilons were used
6702 - fixed bug in presolving while not applying a bound change on a variable in a single-variable constraint (e.g. x1 =
6703 0.03) in cons_linear which is too small, that lead to another bound change in presol_trivial which is not allowed, so
6704 now this bound change will be forced
6705 - fixed SCIPvarIsTransformedOrigvar() in var.c (variables generated by presol_inttobinary returned false)
6706 - fixed bug w.r.t. an assert in presol_inttobinary.c; it was assumed that the aggregation which is performed there will
6707 never lead to an infeasibility, this is not true, see comment in presol_inttobinary.c
6708 - fixed bug in presol_trivial.c trying to fix continuous variables, now uses a less stricter comparison to fix variables
6709 - fixed bug in cons_bounddisjunction.c: presolve may have tried to tighten bounds on a multiaggregated variable (now
6710 upgrades to linear constraint)
6711
6712- Reading, Writing and Messages:
6713 - fixed bug while trying to write a MIP where SCIP needs to flush the lp changes first
6714 - fixed potential resource leak when running out of memory while writing files
6715 - fixed bug in reader_zpl.c which appeared using the parameter `reading/zplreader/parameters`
6716 - fixed bugs in flatzinc readers with constraints that exclusively consist of constants
6717 - fixed bug in reader_gms: correct handling of nonstandard bounds on general integer variables
6718 - fixed buglist entry 35, which was caused by a wrong read in correction when the reading buffer was full in
6719 reader_opb.c
6720 - fixed bugs in reader_fzn.c w.r.t. parsing and solution output in Flatzinc format
6721 - fixed bug in reader_fzn.c w.r.t. comment lines
6722 - fixed bug in reader_opb.c w.r.t. comment lines
6723 - fixed bug in message handler w.r.t. to messages which are longer then `SCIP_MAXSTRLEN`
6724
6725- Heuristics:
6726 - fixed bugs do to `HEUR_TIMING SCIP_HEURTIMING_AFTERPROPLOOP` which appeared during repropagation
6727 - fixed bug in trivial heuristic: the locking solution might have falsely initialized some values to zero
6728 - fixed bug in heur_oneopt.c w.r.t. to SCIPtrySol(); it is necessary that the bound of the solution is check otherwise,
6729 infeasible solution could be accepted as feasible
6730 - fixed bug in heur_trivial.c w.r.t. to debug messages after a solution was freed
6731 - fixed bug for `HEUR_TIMING SCIP_HEURTIMING_BEFOREPRESOL` and modifiable constraints
6732 - corrected wrong assert in DINS heuristic when called for an empty problem
6733 - fixed potential bug in OCTANE heuristic with nonbasic solutions
6734 - fixed bug in sub-MIP heuristics with parameter change if some default plugins are not included
6735 - fixed bug in trivial heuristic with bounds that are greater than the heuristic's infinity value
6736
6737Miscellaneous
6738-------------
6739
6740- As the interface contains several additional callback functions and
6741 parameters for plugins, some effort may be required to compile your
6742 own projects with SCIP 2.0. See also `Changes between version 1.2 and 2.0` in the doxygen
6743 documentation for additional information.
6744
6745@page RN12 Release notes for SCIP 1.2
6746
6747@section RN120 SCIP 1.2.0
6748*************************
6749
6750Features
6751--------
6752
6753- adjusted hard memory limit to (soft memory limit)*1.1 + 100mb in check.sh, checkcount.sh, check_cplex.sh,
6754 check_cluster.sh and check_cbc.sh
6755- new presolving step in cons_knapsack.c, same like `simplifyinequalities` in cons_linear.c
6756- now it's possible to write strings with more than `SCIP_MAXSTRLEN` amount of characters in all message.c functions
6757- the current/root lp can be marked to be no relaxation of the current/root problem
6758- added new preprocessing step (mergeMultiples) in cons_setppc.c where equal variables are merged
6759- Black-box lexicographic dual simplex algorithm; can now run lexicographical dual algorithm (parameter `lp/lexdualalgo`)
6760
6761- Bounds:
6762 - SCIP now has `lazy bounds`, which are useful for column generation: see @ref PRICER_REMARKS `pricer remarks` for an explanation.
6763 Each variable has now two additional `SCIP_Real` parameter which define a lazy lower and upper bound; lazy means that
6764 there exists constraints which implies these (lazy) bounds. If the lazy lower or upper bound is greater or less than
6765 the local lower or upper bound, respectively, then the corresponding bound is not put into the LP. The bounds are set
6766 to minus and plus infinity per default which yields the same behavior as before. With the methods SCIPchgVarLbLazy()
6767 and SCIPchgVarUbLazy() these bounds can be set. This is of interest if SCIP gets used as a branch-and-price
6768 framework. Attention! The lazy bounds need to be valid for each feasible LP solution. If the objective function
6769 implies bounds on the variables for each optimal LP solution, but these bounds may be violated for arbitrary LP
6770 solutions, these bounds must not be declared lazy!
6771 - interval arithmetic functions can work with unbounded intervals added new functions to allow more operations on
6772 intervals, including solving quadratic interval equations
6773
6774- Branching:
6775 - extended hybrid relpscost branching rule by usage of the average length of conflicts a variable appears in
6776 - `early branching`-functionality added: in a branch-and-price code, the user can stop pricing at a node although there
6777 may exist variables with negative reduced costs. In this case, the lp-lowerbound will not be used. The pricer has,
6778 however, the option to return a lower bound. This can be useful for column generation.
6779
6780- Constraints:
6781 - Copy constructors and i/o functionality for constraints: all linear type constraint handlers are able to copy
6782 constraints using the function SCIPgetConsCopy() in scip.h
6783 - the linear constraint handler is able to parse a string in CIP format and create a corresponding linear constraint
6784 - Constraint handler for indicator constraints and parsing them from *.lp and *.zpl files
6785 - the indicator constraint can now try to produce a feasible solution (via heur_trysol)
6786 - one can now write indicator constraints in LP-format
6787 - added constraint handler for quadratic constraints
6788
6789- Cuts:
6790 - added new version of zerohalf cuts from Manuel Kutschka
6791 - added multi-commodity-flow cut separator
6792
6793- Heuristics:
6794 - Heuristics which are applied before root LP
6795 - added heuristic that performs a local search in an NLP (takes only linear and quadratic constraints into account so far)
6796 - added heuristic that gets a solution from other components and tries it (heur_trysol.?)
6797 - new trivial heuristic: tries zero solution, lower and upper bound solution and some variable lock based fixing
6798 - added new timing point, `SCIP_HEURTIMING_DURINGPRICINGLOOP`, for calling heuristics; If this timing point is used the
6799 corresponding heuristics is called during the pricing loop of variables; we also added this timing point to
6800 heur_simplerounding.{h,c} which has the effect that a LP solution which satisfies all integrality conditions during
6801 the pricing loop is detected
6802
6803- Interfaces:
6804 - added first version of an interface to NLP solvers (type_nlpi.h, struct_nlpi.h, nlpi.h, nlpi.c, nlpi_oracle.h, nlpi_oracle.c)
6805 - Preliminary support of non-convex MIQCPs: Constraint handler for quadratic constraints, NLP heuristic and
6806 Ipopt interface, see \ref cons_quadratic.h.
6807 - There are LP-interfaces to QSopt and Gurobi (rudimentary).
6808
6809- Reader and Writer:
6810 - added reader and writer for FlatZinc models (reader_fzn.{c,h})
6811 - added writer for GAMS models (reader_gms.{c,h})
6812
6813Performance improvements
6814------------------------
6815
6816- Enhanced MCF cuts: stable version, used by default
6817- replaced some function calls in loop conditions
6818- in sepa_cmir.c, if mksetcoefs is invalid for delta=1 no other values of delta are tested anymore
6819- changed the timing of the feasibility pump in case of pricing
6820- removed changing of update rule to `ETA` from standard soplex update `Forrest-Tomlin` in lpi_spx.cpp
6821- improved memory usage in heur_octane.c
6822- improved reading time of opb-files, due to using a hashtable for all `and`-constraints
6823- improved performance of merging variables in mergeMultiples() in cons_knapsack.c
6824- improved performance in tightenWeightsLift() and SCIPseparateRelaxedKnapsack() in cons_knapsack.c, due to now
6825 sparse-cleaning `global` arrays instead of using BMSclearMemory... functions for cleaning local arrays each time
6826- improved performance in SCIPcliquelistRemoveFromCliques()
6827- improved performance in SCIPcalcCliquePartition()
6828- improved performance in SCIPvarGetActiveRepresentatives() in var.c
6829
6830- Presolving:
6831 - improved pairwise presolving in cons_and.c due to using a hashtable
6832 - improved pairwise presolving in cons_xor.c due to using a hashtable
6833
6834Interface changes
6835-----------------
6836
6837- A significant change for C++ users is that all include files of SCIP
6838 automatically detect C++ mode, i.e., no `extern `C`` is needed anymore.
6839- Reader for Flatzinc and GAMS models
6840
6841### New and changed callbacks
6842
6843- The callback SCIP_DECL_PRICERREDCOST(x) in the \ref PRICER `pricers` has two new parameters:
6844 + A `result` pointer determines whether the pricer guarantees that there exist no more variables. This allows for early branching.
6845 + A pointer for providing a lower bound.
6846
6847- The \ref CONS `constraint handlers` have two new callback methods (see type_cons.h for more details):
6848 + SCIP_DECL_CONSCOPY(x): this method can be used to copy a constraint.
6849 + SCIP_DECL_CONSPARSE(x): this method can be used to parse a constraint in CIP format.
6850
6851### Deleted and changed API methods
6852
6853- SCIPcalcMIR() in scip.h has two new parameter `mksetcoefsvalid` and `sol`. The parameter `mksetcoefsvalid` stores
6854 whether the coefficients of the mixed knapsack set (`mksetcoefs`) computed in SCIPlpCalcMIR() are valid. If the mixed
6855 knapsack constraint obtained after aggregating LP rows is empty or contains too many nonzero elements the generation of the
6856 c-MIR cut is aborted in SCIPlpCalcMIR() and `mksetcoefs` is not valid. The input parameter `sol` can be used to separate a
6857 solution different from the LP solution.
6858- new parameter `set` in SCIPconsSetInitial().
6859- some interval arithmetic method take an additional argument to denote which value stands for infinity in an interval
6860
6861- Variables:
6862 - SCIPgetVarClosestVlb() and SCIPgetVarClosestVub() in scip.h have a new parameter `sol`. It can be used to obtain the closest
6863 variable bound w.r.t. a solution different from the LP solution.
6864 - new parameters `lowerbound` and `result` in type_pricer.h: lowerbound can save a lower bound computed by the pricer,
6865 result indicates whether the pricer guarantees that there exist no more variables if no variable was found
6866
6867### New API functions
6868
6869- new methods to deactivate a pricer SCIPdeactivatePricer() in scip.c
6870- new methods in pub_misc.h/misc.c to access hash map lists and elements of a hash map list and to clear all entries in a hash map
6871- SCIPsetProbName() to set problem name in scip.h/c (SCIPprobSetName() in prob.h/c)
6872
6873- Objective:
6874 - SCIPgetTransObjscale() and SCIPgetTransObjoffset() in scip.c
6875 - SCIPaddObjoffset() in scip.h; sets offset of objective function
6876 - SCIPgetOrigObjoffset() in scip.h; returns the objective offset of the original problem
6877 - SCIPgetOrigObjscale() in scip.h; returns the objective scale of the original problem
6878
6879- Constraints:
6880 - detectRedundantConstraints() in cons_xor.c and necessary hash-functions for fast pairwise presolving
6881 - SCIPparseCons() in scip.h; parses constraint information (in cip format) out of a string
6882 - SCIPgetConsCopy() in scip.h; which copies a constraint of the source SCIP
6883
6884- Relaxation:
6885 - SCIPisLPRelax() and SCIPisRootLPRelax() in scip.c and scip.h returning whether the current/root LP is a
6886 relaxation of the current/root problem and thus defines a valid lower bound
6887 - SCIPlpSetIsRelax() and SCIPlpSetRootLPIsRelax() in lp.c and lp.h to set the information, whether the lp is a valid relaxation;
6888 this information is per default set to true and constraint be used. The aggregated version has only 2 linear constraints the
6889 default linearization has nvars + 1
6890
6891- Sort:
6892 - extended the sort template functions in sorttpl.c with a `five` array; now it possible to used this template to sort
6893 up to five arrays
6894 - new interface methods SCIPcolSort(), SCIProwSort(), SCIPcolGetIndex()
6895 - added SCIPsortPtrPtrLongInt() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines
6896 in misc.c
6897
6898- Variables:
6899 - SCIPprintNodeRootPath() in scip.h This method prints all branching decisions on variables from the root to the given node
6900 - SCIPnodeGetParentBranchings(), SCIPnodeGetAncestorBranchings(), SCIPnodeGetAncestorBranchingPath(); These methods return
6901 the set of variable branchings that were performed in the parent node / all ancestor nodes to create a given node
6902 - SCIPchgVarLbLazy() and SCIPchgVarUbLazy() in scip.h; These methods can be used to change the lazy lower or
6903 upper bound of a variable; This might has the consequences that the bounds of the corresponding variable is not in
6904 LP. This is the case if the lazy lower or upper bound is greater or less than the local lower or upper bound, respectively
6905 - SCIPvarGetLbLazy() and SCIPvarGetUbLazy() in pub_var.h; These methods return the lazy lower or upper bound, respectively
6906 - SCIPvarCompareActiveAndNegated() and SCIPvarCompActiveAndNegated() in pub_var.h for comparing variables
6907 negated, active or fixed the same way
6908 - SCIPparseVars() in scip.h; parses variable information (in cip format) out of a string
6909 - SCIPgetNFixedonesSetppc() and SCIPgetNFixedzerosSetppc() in cons_setppc.{h,c}; these methods returns
6910 current (local) number of variables fixed to one/zero in the given setppc constraint
6911 - SCIPgetVarConflictlengthScore(), SCIPgetVarAvgConflictlength(), SCIPgetAvgConflictlengthScore() and their pendants for the current run
6912 - added function SCIPvarsGetProbvarBinary() in pub_var.h; gets active, fixed, or multi-aggregated problem variables of
6913 binary variables and corresponding negated status
6914
6915### Interfaces to external software
6916
6917- LP Interfaces:
6918 - heavily revised Mosek interface
6919 - new interface to QSopt due to Daniel Espinoza
6920 - First version of LP interfaces to Gurobi and QSopt
6921 - Major performance improvements in LP interfaces to Clp, Mosek and SoPlex
6922
6923- External Software:
6924 - adjusted interface to ZIMPL (reader_zpl.{c,h} for ZIMPL version 2.10; this interface should also work with older ZIMPL versions
6925 - Adjusted interface to Zimpl version 3.0.0
6926 - added first version of an interface to Ipopt (only QCP, no deletion of vars/cons allowed; nlpi_ipopt.(h|c))
6927
6928- SCIP Interfaces:
6929 - On http://code.google.com/p/python-zibopt/source/checkout you find a beta
6930 version of a python interface to SCIP implemented by Ryan J. O'Neil.
6931
6932### Changed parameters
6933
6934- removed parameter `constraints/and/initiallp` since it is not needed anymore;
6935- set parameter `constraints/and/sepafreq` default value to 1
6936- display character of oneopt heuristic changed to `b`
6937
6938### New parameters
6939
6940- `branching/relpscost/advanced/conflenscore`, default value 0.001
6941- `constraints/and/aggrlinearization` in cons_and.c, aggregated version of the linearization
6942- `constraints/and/enforcecuts` in cons_and.c, should cuts be separated during LP enforcing?
6943- `constraints/and/presolusehashing` in cons_and.c, should pairwise presolving use hashing?, default TRUE
6944- `constraints/countsols/sollimit` in cons_countsols.c, counting stops, if the given number of solutions were found (-1: no limit)
6945- `constraints/xor/presolusehashing` in cons_xor.c, should pairwise presolving use hashing?, default TRUE
6946- `heuristics/oneopt/duringroot`, default value TRUE
6947
6948Build system
6949------------
6950
6951### Makefile
6952
6953- extend Makefile to link against Ipopt if `IPOPT=true` is set
6954
6955Fixed bugs
6956----------
6957
6958- fixed wrong use of pointer in lp.c
6959- fixed bug with array dimension not reset to zero when array is freed in pseudoobj propagator
6960- fixed bug with enforcement of pseudo solutions: if pseudo solution is choosen because LP hit a limit, it has to be
6961 enforced in any case
6962- fixed potential bug in coloring example: SCIPcreateChild() is now given an estimate in terms of the transformed
6963 problem by SCIPgetLocalTransEstimate(), no longer the estimated original problem value. Also clarified this in the
6964 comments for SCIPcreateChild()
6965- fixed compiler warning `warning: dereferencing type-punned pointer will break strict-aliasing rules` which resuts in
6966 scip-crashes with gcc version 4.4.0
6967- adjusted assert in var.c
6968- fixed bug in SCIPvarGetActiveRepresentatives() in var.c
6969- fixed bug with objective limit in lp.c: previously the infinity value of SCIP was used as default - now the value of
6970 LPI is used. In the earlier version in many cases the problems where never infeasible.
6971- added and adjusted some asserts, initialized some values
6972- increased the numerical stability of coefficient tightening for Big M formulations
6973- fixed bug with incorrect pseudo activities when objective of a variable switches sign in linear constraint handler
6974- fixed bug with empty constraints in several writing routines
6975- fixed `GGT-Kaibel-Bug` in var.c, prop_pseudoobj.c and cons_varbound.c that occured while computing new values using
6976 infinity values
6977
6978- Bounds:
6979 - fixed bug in coefficient tightening with infinite bounds
6980 - fixed bug in solve.c: in case lowerbound >= upperbound, SCIPsolveIsStopped() returned `SCIP_STATUS_GAPLIMIT`
6981
6982- Nodes:
6983 - fixed bug in SCIPsolveNode() concerning the case that the time limit was hit while solving the LP relaxation of a
6984 subproblem which is already an LP (branching on pseudo solution is not possible)
6985 - fixed bug in vbc tools concerning of marking probing nodes
6986 - fixed bug in solve.c with nodes which are marked to be repropagated while enforcement
6987
6988- Variables:
6989 - fixed possible infinite loop while multiaggregating a variable in var.c
6990 - fixed bug in SCIPgetSolVals() similar to SCIPgetSolVal(): try to get original variables of transformed ones if the
6991 solution lives in original space
6992
6993- Pricing:
6994 - fixed potential bug: restarts are now only done if no active pricers exist
6995 - fixed bug in SCIPlpSolveAndEval(): if fastmip and pricers enabled and objlimit was reached but CPLEX did not perform
6996 the final pivot step in order to exceed the objlimit, do one additional simplex step with pricing strategy steepest
6997 edge, if this doesn't suffice, turn off fastmip temporarily and solve again. Also consider solstat of the new
6998 solution.
6999 - fixed bug with invalid pseudo solution (lower bound was always >= 0) when using pricing.
7000 - fixed bug in SCIPfreeProb() in scip.c: all pricers are deactivated now
7001
7002- Memory:
7003 - now frees debug memory
7004 - fixed bug with exponential complexity for reallocating memory in SCIPvarGetActiveRepresentatives() in var.c
7005 - fixed casting of void* pointers in memory.h for C++, adjusted the same for C in memory.h and due to that adjusted all
7006 header files(set whole files in extern `C`) and cpp-files(removed unnecessary extern `C` lines)
7007 - removed memory leak in connection with freeing branch and bound nodes: focusnode was not freed if both children could
7008 be cut off due to bounding
7009
7010- Reading and Writing:
7011 - corrected bug in reader_lp.c: earlier read bounds were thrown away (implementation was not conforming to standard)
7012 - fixed bug in reader_lp.c with respect to constraint and variable names which start with two or more dots `..`
7013 - fixed bug in all readers w.r.t. SCIPgetProbvarLinearSum()
7014 - fixed bug in reader_mps.c with respect to corrupted files
7015 - fixed bug in reader_mps.c with respect to writing transformed problems
7016 - changed wrong writing of mps files due to constraints without any name
7017 - fixed a bug during reading debug solution file
7018 - fixed bug in case of reading an objective function in opb format with multiple occurrences of the same variable
7019 - fixed bug in case of reading an objective function in lp format with multiple occurrences of the same variable
7020 - fixed a wrong fix of a reading bug, which was in reality a writing bug in MPS format; integer variables in mps format
7021 without bounds are binary variables, if the bound of an integer variable is infinity you have to write this bound
7022
7023- Separation:
7024 - fixed bug in sepa_cmir.c, sepa_mcf.c and sepa_flowcover.c: sol different to LP solution is now separated
7025 - corrected two asserts in sepa_redcost.c (reduced costs can be negative for fixed variables: qsopt uses this)
7026 - fixed bug in sepa_zerohalf.c; replacement of own sorting functions by template functions was incorrect
7027 - fixed bug in var.c, cons_knapsack.c and sepa_flowcover.c: variable bounds corresponding to implication are not
7028 generated if coefficient is large, variable bounds with large coefficients are ignored for construction of knapsack
7029 and snf relaxations
7030 - fixed bug in sepa_impliedbound.c concerning redundant implications
7031
7032- Cuts:
7033 - fixed bug in sepa_cmir.c concerning uninitialized mksetcoefs (if MIR-cut generation is aborted because the aggregated
7034 constraint is empty or contains too many nonzero elements mksetcoefs is invalid)
7035 - interrupts optimization process if a node will be cutoff, which allows the solution
7036 - fixed bug in sepa_impliedbounds.c and sepa_intobj.c: if separating a sol, this sol is now also given to SCIPaddCut()
7037 so that the efficacy of the cut is now computed correctly
7038 - fixed bug in solve.c caused by integer overflow due to setting the number of cuts to INT_MAX
7039
7040- Presolving:
7041 - fixed wrong result in check.awk, if infeasible problems are stopped in presolving
7042 - fixed exponential calculation of solution values during check of original solution, therefore changed
7043 SCIPvarGetActiveRepresentatives() in var.c and flattened all multiaggregated vars at the end of presolving in
7044 exitPresolve()
7045 - fixed bug with wrong abort criterion in presolving
7046 - fixed bug in presol.c caused by not reseting presolver-wasdelayed status
7047 - fixed bug in SCIPconsSetInitial() that occurred in pairwise presolving: add or delete constraint in initconss when
7048 changing the initial flag
7049
7050- Constraints:
7051 - fixed bug in cons.c caused by not resetting conshdlr data after restart
7052 - fixed memory error in cons_countsols.c
7053 - fixed assert in cons_and.c method SCIP_DECL_CONSINITSOL(consInitsolAnd)
7054 - fixed bug in cons_countsols.c we respect to warning message that `The current parameter setting might cause ...`
7055
7056- Knapsack Constraint Handler:
7057 - fixed wrong assert in cons_knapsack.c and handled a special this case in simplifyInequalities()
7058 - fixed some bugs in simplifyInequalities() in cons_knapsack.c
7059 - fixed bug in mergeMultiples() in cons_knapsack.c
7060 - adjusted ConsData and ConsHdlrData in cons_knapsack.c
7061 - fixed compiler warning caused by no initialization of two integer in cons_knapsack.c
7062 - fixed bug in cons_knapsack.c caused by having a multi-aggregated variable in a knapsack constraint, now applyFixing is
7063 able to resolve a binary multi-aggregation with integral values
7064
7065- Linear Constraint Handler:
7066 - fixed infinity loop in simplify inequalities in cons_linear.c
7067 - fixed bug in cons_linear.c: do not select variable as slack variable for multiaggregation in convertLongEquality if it
7068 has been marked as not-multiaggregable
7069 - fixed bug in cons_linear.c: also do not multiaggregate variables in dual preproccessing if it has been marked as
7070 not-multiaggregable
7071 - fixed bug in cons_linear.c: slight decrease of epsilon in order to make sure that scaled coefficients are really
7072 integral
7073 - fixed bug in chgRhs() and chgLhs() of cons_linear.c: after changing lhs or rhs of a constraints lhs <= rhs has to be
7074 satisfied without numerical tolerances
7075
7076- Heuristics:
7077 - added and changed some SCIPisStopped() calls in several heuristics
7078 - fixed bug in oneopt heuritic with start solution which has become infeasible due to global bound changes
7079
7080- Interfaces:
7081 - corrected several bugs in the Clp-interface concerning return values
7082 - fixed potential interface bug: time limits of 0.0 are not anymore passed to the LP solver, which may have caused
7083 errors
7084
7085@page RN11 Release notes for SCIP 1.1
7086
7087@section RN110 SCIP 1.1.0
7088*************************
7089
7090Features
7091--------
7092
7093- SCIP can now count integer feasible solutions for IPs/CIPs (without continuous variables) (see SCIPcount())
7094- check.awk now uses TeX package supertabular which supports automatic pagebreak
7095- struct `SCIP_Stat` has now two additional variables: `nprobboundchgs`, `nprobholechgs`; these are used to fix the domain
7096 reduction counts in sepa.c, cons.c, branch.c and prop.c; this means, that now the domain reduction counts are reduced
7097 by those domain reduceds which are preformed during probing
7098- added capabilities to flatten the (multi)-aggregation graph of variables
7099- pseudoobj propagator now also propagates the global lower (dual) bound
7100- new heuristic DINS (distance induced neighborhood search by Ghosh)
7101
7102- Output:
7103 - SCIP can now output a picture of the constraint matrix in PPM format.
7104 - output of real values is now done with 15 digits after the decimal point
7105 - Extended the capabilities of SCIP to output problems in different formats (LP, MPS, CIP, ...). You can output the original and
7106 transformed problem. Furthermore, generic names can be given to the variables and constraints.
7107 - The feasibility test for solutions at the end of the execution now outputs more useful information.
7108 This made some changes in the interface of constraint handlers necessary.
7109
7110- Presolving:
7111 - added predefined settings file presolving/aggressive.set
7112 - new presolver boundshift (presol_boundshift.{c,h}); this presolver is currently turned off with default parameter setting
7113
7114- Constraints:
7115 - linear constraint handler now detects continuous variables that are implicit integer in dual presolve
7116 - replaced some old sorting methods in cons_knapsack.c, heur_octane.c, sepa_flowcover.c and presol_probing.c through
7117 SCIPsort...() interfaces, adjusted misc.{c,h} and pub_misc.h for these changes
7118 - cons_countsols.c is now able to store the collected solution if required
7119 - added first version of SOS type 1 constraint handler (cons_sos1.{c,h})
7120 - added first version of SOS type 2 constraint handler (cons_sos2.{c,h})
7121 - less aggressive scaling in linear constraint handler presolve to improve numerics
7122 - added first version of constraint handler cons_countsols.{c,h}
7123
7124- Reader:
7125 - added ccg-reader (weighted column connectivity graph)
7126 - added reader for pseudo-Boolean problems (reader_opb.{c,h})
7127 - the ZPL reader is now able to pass a starting solution to SCIP
7128 - the MPS reader is now able to write a problem in MPS format
7129 - the ZIMPL reader now understands SOS type 1 and 2 constraints
7130 - the LP reader reads SOS constraints of type 1 and 2
7131 - the MPS reader reads the SOS section (but cannot yet handle `MARKERS`)
7132
7133- LPI:
7134 - The SoPlex LPI can now write basis files.
7135 - revised lpi_clp.cpp (many small changes, in particular writing and reading of bases)
7136 - added FASTMIP settings in lpi_clp.cpp that try to improve the performance of Clp as much as possible
7137
7138- Cuts and Separation:
7139 - the c-MIR separator now also tries to get rid of implicit integer variables by aggregation
7140 - allow cut selection based on support of inequality in orthogonality computation
7141 - disabled zerohalf cuts by default
7142 - adjusted all predefined settings files, e.g., `settings/cuts/fast.set`, such that they are consistent wrt removed,
7143 added and changed parameter values of scip.
7144 - New cutting plane separator MCF (beta version).
7145 - new separator sepa_zerohalf.{c,h}; separates {0,1/2}-Cuts according to Caprara and Fischetti
7146
7147Performance improvements
7148------------------------
7149
7150- heavily decreased the usage of SCIPisStopped(), which costs system time
7151- small performance improvement of c-MIR aggregation heuristic
7152- reworked strong branching in lpi_clp.cpp (scaling works now, bounds can be trusted)
7153
7154- Constraints:
7155 - The preprocessing has been revised. It now applies bound computations in a numerically more stable way. The pairwise
7156 comparison of linear, logicor, and setppc constraints has been improved.
7157 - better branching in SOS1/SOS2 constraints
7158 - fixed performance bug with large number of unnamed constraints that will kill the name hash table (now, unnamed
7159 constraints are not put into the hash table)
7160
7161- Cuts and Separation:
7162 - improved the performance of SCIPcalcMIR() and SCIPcalcStrongCG() by exploiting sparsity
7163 - improved performance of SCIPvarGetLPSol(), which affects many parts of the code, in particular Gomory and strong CG cuts
7164 - do not calculate MIR and StrongCG cut aggregations if number of nonzeros in aggregated row is too large
7165
7166- Presolving:
7167 - improved pairwise presolving in cons_linear.c: reduced cache misses, reduced number of SCIPisStopped() calls and
7168 included detecting of redundant constraints with hash table in advance
7169 - tighter memory limits in knapsack presolve lifting procedure to avoid overly expensive presolving
7170 - included detecting of redundant constraints with hash table in advance in cons_logicor.c and limit other pairwise
7171 presolving
7172 - included detecting of redundant constraints with hash table in advance in cons_setppc.c and limit other pairwise
7173 presolving
7174 - limit pairwise presolving in cons_linear.c
7175
7176Examples and applications
7177-------------------------
7178
7179- Added an example for the graph coloring problem in `examples/Coloring`, showing the usage of column generation.
7180- added SOS2 example
7181- extended TSP example
7182
7183Interface changes
7184-----------------
7185
7186### New and changed callbacks
7187
7188- New callback method SCIP_DECL_READERWRITE(x) in type_reader.h; this method is called to write a problem to file
7189 stream in the format the reader stands for; useful for writing the transformed problem in LP or MPS format. Hence,
7190 also SCIPincludeReader() has changed.
7191- The callback \ref CONSCHECK (SCIP_DECL_CONSCHECK()) in the constraint handlers now has a new parameter `printreason` that tells
7192 a constraint handler to output the reason for a possible infeasibility of the solution to be checked using
7193 SCIPinfoMessage(). Have a look at one of the constraint handlers implemented in SCIP to see how it works. This
7194 methodology makes it possible to output the reason of a violation in human readable form, for instance, for the check
7195 at the end of a SCIP run, where the obtained best solution is checked against the original formulation.\n This change
7196 often has little effect on C-implementations, since this parameter can be safely ignored with respect to the
7197 correctness of the code. The corresponding C++ method scip::ObjConshdlr::scip_check(), however, has to be extended
7198 and will not compile otherwise.
7199- added new LPI pricing option `SCIP_PRICING_LPIDEFAULT`, such that every LP interface can set the default pricing
7200 strategy on its own (`auto` is not useful for this, because for CPLEX, for example, SCIP seems to be worse with `auto`
7201 then with `steepest edge`)
7202- Added user pointer to callback methods of hash table, see pub_misc.h.
7203
7204### Deleted and changed API methods
7205
7206- SCIPgetVarRedcost() now returns 0 for variables that have been aggregated out or removed in presolving.
7207 reduced cost in case of infeasible LPs)
7208- new parameter `maxfrac` for SCIPcalcStrongCG()
7209- new parameter `maxmksetcoefs` for SCIPcalcMIR() and SCIPcalcStrongCG() methods
7210- new parameter `conshdlrname` in SCIPincludeLinconsUpgrade()
7211
7212- Problem:
7213 - new parameters `extension` in SCIPreadProb() defining a desired file format or `NULL` if file extension should be use
7214 - New parameters `extension` and `genericnames` in SCIPprintTransProblem(), SCIPprintOrigProblem(),
7215 SCIPwriteOrigProblem(), and SCIPwriteTransProblem() defining the requested format or `NULL` for default CIP format
7216 and using generic names for the variables and constraints. Examples are
7217 - SCIPprintTransProblem(scip, NULL, NULL, TRUE) displays the transformed problem in CIP format with
7218 generic variables and constraint names
7219 - SCIPprintOrigProblem(scip, NULL, `lp`, FALSE) displays the original problem in LP format with
7220 original variables and constraint names.
7221
7222- Sorting:
7223 - expand sorttpl.c by some parameters
7224 - changed some names for sorting methods
7225 - replaced sorting methods SCIPbsort...() by faster (quicksort/shellsort) algorithms SCIPsort...() Note that the order
7226 of the parameters has been changed to simplify the template code in sorttpl.c!
7227
7228- Checking:
7229 - SCIPcheckSolOrig() is restructured. The last two parameters have changed. They are now bools indicating
7230 whether the reason for the violation should be printed to the standard output and whether all violations should be
7231 printed. This reflects the changes in the constraint handlers above, which allow the automation of the feasibility
7232 test. The pointers to store the constraint handler or constraint are not needed anymore.
7233 - the parameter list of the method SCIPcheckCons() (scip.h) has changed; the new advatage is, that SCIP can print the
7234 reason for the violation of a constraint as for as the constraint handler supports that
7235 - the parameter list of the method scip_check() (objconshdlr.h) has an additional parameter `printreason` see for
7236 explanation the previous point
7237
7238### New API functions
7239
7240- LPI now has a function SCIPlpiGetSolverPointer() that returns a solver dependent pointer. This can be used to directly
7241 access the LP solver. This should, of course, only be used by people that know exactly what they are doing.
7242- added capabilities to avoid multi-aggregation of a single variable by setting a corresponding flag (SCIPmarkDoNotMultaggrVar())
7243- SCIPgetProbvarLinearSum()
7244- SCIPgetResultantAnd() which returns the resultant variable of an `and` constraint
7245- SCIPchgChildPrio() to change the node selection priority of the given child
7246- SCIPconsGetPos()
7247- SCIPrepropagateNode() to mark a node for repropagation
7248- SCIPcount() (in cons_countsols.h) for counting all feasible solution of a given CIP
7249- SCIPcreateRootDialog() (in dialog_default.h) which creates a root dialog
7250- SCIPgetVectorEfficacyNorm()
7251- SCIPseparateRelaxedKnapsack() in cons_knapsack.h
7252- SCIPgetCutoffdepth() which returns the depth of first node in active path that is marked being cutoff
7253- SCIPflattenVarAggregationGraph()
7254- SCIPclockGetLastTime()
7255- SCIPcalcHashtableSize() to get a reasonable hash table size
7256- SCIPgetVarFarkasCoef() and SCIPgetColFarkasCoef() to get the farkas coefficient of a variable (analogon of
7257- SCIPgetRepropdepth() to get the depth of first node in active path that has to be propagated again
7258- SCIPmajorVersion(), SCIPminorVersion() and SCIPtechVersion() returning the corresponding version
7259
7260- Read, Write and Print:
7261 - SCIPprintSysError() which encapsulates the strerror_r calls, the NO_STRERROR_R flag switches between the use
7262 of strerror_r and strerror inside
7263 - SCIPsnprintf() safe version of snprintf (and sprintf)
7264 - SCIPreaderCanRead() and SCIPreaderCanWrite() in pub_reader.h, these return TRUE if the corresponding
7265 reader is capable to read or write, respectively
7266 - SCIPwriteOrigProblem(), e.g., SCIPwriteOrigProblem(scip, `orig.lp`, NULL, FALSE) prints the original
7267 problem in LP format in the file `orig.lp`
7268 - SCIPwriteTransProblem(), e.g., SCIPwriteTransProblem(scip, NULL, NULL, FALSE) displays the transformed problem in CIP format
7269
7270- Heuristics:
7271 - SCIPcutGenerationHeuristicCmir() in sepa_cmir.h
7272 - SCIPheurGetTimingmask() and SCIPheurSetTimingmask()
7273
7274- Sorting:
7275 - added some downwards-sorting methods
7276 - SCIPbsortInd()
7277 - SCIPsortedvecInsert...(), SCIPsortedvecInsertDown...(), SCIPsortedvecDelPos...(),
7278 SCIPsortedvecDelPosDown...(), SCIPsortedvecFind...() and SCIPsortedvecFindDown...() to manage sorted vectors or
7279 groups of vectors of various data types that are sorted w.r.t. the first vector
7280
7281### Command line interface
7282
7283- advanced reading and writing dialog in interactive shell
7284
7285### Interfaces to external software
7286
7287- Many changes in the SoPlex interface: The current one is tailored towards SoPlex 1.4 (aka 1.3.3). All SoPlex functions
7288 (where applicable) should now have an exception handling. The Bugfix for adding columns has been moved to SoPlex. One
7289 can use ROW representation. Reading/writing of a basis has been implemented.
7290
7291### Changed parameters
7292
7293- changed default frequency parameters for RINS, Local Branching, Crossover and Mutation heuristic This should not
7294 change the performance but happened just for consistency reasons
7295- changed parameter default values for the priority of presolver `dualfix` and `inttobinary`
7296- removed parameter `separating/cmir/maxtestdeltaroot`
7297- new value `l` for parameter `lp/pricing`, which is the new default
7298
7299### New parameters
7300
7301- `constraints/and/linearize` to enable linearization of all <and> constraints (in presolving),
7302- `constraints/and/initiallp` to turn on, off, or `auto` that the LP relaxation of the AND constraints are in the initial LP;
7303- `constraints/countsols/collect` to enable the storing of the solutions; default value FALSE;
7304- `constraints/indicator/addCoupling` to enable generation of relaxation
7305- `constraints/indicator/branchIndicators` to decide whether it is branched on indicator constraints in enforcing
7306- `constraints/indicator/genLogicor` to decide whether logicor constraints instead of cuts are generated
7307- `constraints/indicator/sepaAlternativeLP` to decide whether separation takes place using the alternative LP
7308- `constraints/linear/aggregatevariables` to search for aggregations in equations in the presolving step
7309- `constraints/linear/dualpresolving` to disable dual presolving step in the linear constraint handler; default value is TRUE
7310- `constraints/linear/simplifyinequalities` to enable a simplification step for inequalities; default value is set to FALSE = disabled
7311- `constraints/linear/upgrade/binpack` to enable or disable the linear upgrading process
7312- `constraints/linear/upgrade/eqknapsack` to enable or disable the linear upgrading process
7313- `constraints/linear/upgrade/invarknapsack` to enable or disable the linear upgrading process
7314- `constraints/linear/upgrade/knapsack` to enable or disable the linear upgrading process
7315- `constraints/linear/upgrade/logicor` to enable or disable the linear upgrading process
7316- `constraints/linear/upgrade/setppc` to enable or disable the linear upgrading process
7317- `constraints/linear/upgrade/varbound` to enable or disable the linear upgrading process
7318- `constraints/linear/presolusehashing` to use hashing comparison in cons_linear.c; default value is TRUE
7319- `constraints/logicor/presolusehashing` to use hashing comparison in cons_logicor.c; default value is TRUE
7320- `constraints/setppc/presolusehashing` to use hashing comparison in cons_setppc.c; default value is TRUE
7321- `constraints/SOS1/branchNonzeros` to decide whether SOS1 constraint with largest number of nonzero variables is picked for branching
7322- `constraints/SOS1/branchSOS` to enable or disable branching on SOS1 constraints
7323- `heuristics/feaspump/beforecuts` to allow the feaspump to be called before cut separation
7324- `heuristics/mutation/minimprove`
7325- `presol/donotmultaggr` which disables multiaggregation for all variables of the problem
7326- `separating/cmir/densityoffset` to allow for more c-MIR cuts on small models
7327- `separating/orthofunc` to choose function for scalar product computation in orthogonality test
7328
7329Testing
7330-------
7331
7332- updated mmm.{test,solu}, mittelmann.{test,solu}, miplib3.solu, miplib.solu, shortmiplib.test and added
7333 mittelmann_current.test, mittelmann_old.test
7334- added test scripts for testing counting (make testcount)
7335- removed tag make testpre (useless without corresponding scripts)
7336- added tag testcount (make testcount); this allows for testing counting problem
7337- replaced tcsh by bash and gawk by awk in all check scripts to achieve higher compatibility
7338
7339Build system
7340------------
7341
7342### Makefile
7343
7344- added `make/make.project` as default make include for external projects using SCIP
7345- added possibility to compile shared libraries in makefiles (and added `make/make.linux.x86.gnu.opt-shared`)
7346- replaced <string> by <cstring> in all C++-interfaces to get `strlen()` included (gcc-4.3 gave an error)
7347- Moved -rpath option for ld to linux-specific Makefiles.
7348- Re-activated readline library on darwin/ppc.
7349
7350- Flags:
7351 - added in all `make/make.*` `GMP_FLAGS` and `GMP_LDFLAGS`
7352 - new flag GMP with values (`auto`, `true and `false`); in case of `auto` the library gmp is linked if ZIMPL is
7353 included
7354 - adapted all makefiles of the examples accordingly
7355
7356- LP:
7357 - modified makefiles to accept ZIMPLOPT and LPSOPT flags (with values `opt` or `dbg` and default being `opt`), and
7358 removed `LPS=spxdbg` and `LPS=clpdbg`
7359 - added target spx132 for SoPlex version 1.3.2
7360
7361Fixed bugs
7362----------
7363
7364- fixed CTRL-C if NO_SIGACTION is set (e.g., for MinGW)
7365- added checks whether a plugin (handler) has already been included to avoid later complications e.g. with parameters.
7366- fixed bug with wrong `tightened` return value of some of the change bounds methods
7367- forced full propagation in presolving -> this fixes a bug that implied that variable locks became inconsistent
7368- replaced calls to perror() by SCIP error message using strerror(errno); this avoids problems with the error output
7369 stream
7370- fixed bug in method SCIPgetProbvarLinearSum()
7371- fixed bug with errors occurring in sub-MIPs. Search is only aborted in dbg mode, in opt mode a warning will be printed
7372- fixed bug in tclique-graph datastructure concerning insertion of edges into nonempty graph
7373- corrected bug in SCIPtreeBranchVar() (tree.c): several comparison functions needed a `feas`.
7374- fixed bug in SCIPtightenVarLb/Ub() in scip.c concering forcing a bound change (bound improvement is checked now)
7375- improved stage checking for bound computation
7376- fixed usage of command test for string comparison in check-scripts (now compatible with ubuntu)
7377- replaced sprintf and snprintf by SCIPsnprintf() fixed potential bug with overlong strings
7378- corrected bug in the case when soplex threw an exception in autopricing
7379- fixed bug in SCIPvarGetOrigvarSum() concerning the corner case the a negated variable has no parent variable in
7380 original problem
7381
7382- Aggregation:
7383 - avoid aggregation of implicit integers with fractional aggregation scalars
7384 - fixed bug in aggregateActiveIntVars(): If a < 0, multiply a*x + b*y == c by -1 (algo for finding initial solution does
7385 only work for a > 0).
7386 - avoiding aggregation that removes information about implicitly integer variables (removes bug)
7387 - fixed bug with exponential running times due to complicated recursive multi-aggregation
7388 - corrected bug in var.c occuring during applying boundchanges in varUpdateAggregationBounds method
7389
7390- Constraints:
7391 - fixed bug that a missing CONSTRANS in constraint handler leads to `NULL` pointer as constraint data for the copied
7392 constraints instead of pointer copies of the consdata (as explained in the constraint handler `HowTo`)
7393 - fixed bugs in second part of consdataTightenCoefs(): Removed min/maxleftactisinfinity (definition was not correct),
7394 fixed calculation of min/maxleftactivity and removed asserts concerning whether all redundant vars were deleted (led
7395 to different behavior in debug and opt mod).
7396 - fixed typo in documentation: default value for `dynamic` parameter is FALSE for all constraint handlers!
7397 - fixed bug in preprocessing of SOS2 constraints (cons_sos2.c)
7398 - fixed bug in cons_countsols.c concerning variable locking
7399 - fixed bug in cons_varbounds.c, concerning SCIPaddVarVlb() and SCIPaddVarVub()
7400 - fixed bug in applyFixings() in cons_varbound.c concerning tightening the bound of a variable left in a redundant
7401 constraint (bound change is forced now)
7402
7403- Heuristics:
7404 - fixed bug with useless objective cutoff in LNS heuristics
7405 - removed bug for values greater than (-)infinity, heur_shifting.c, heur_intshifting.c, heur_rounding.c, heur_oneopt.c
7406 - fixed bug with errors occurring in heuristic LPs. In opt mode a warning will be printed, abort in dbg mode
7407
7408- Linear Constraints:
7409 - fixed bug with wrong update of activities in linear constraints after global upper bound changes
7410 - fixed bug in preprocessConstraintPairs() in cons_linear.c concerning updating the flags of the constraint that stayes
7411 in the problem (nonredundant information were lost before)
7412 - fixed bug in cons_linear.c caused by comparing two infinity values during checking of using variable as slackvariable
7413 - removed bug for rhs/lhs greater than (-)infinity, cons_linear.c
7414 - removed bug caused by hashcomparison for non-sorted constraints, cons_linear.c
7415 - fixed bugs with wrong presolving due to cancellation in (res-)activities in cons_linear.c
7416 - removed BOUNDSCALETOL adjustment in cons_linear.c. This fixes bug with slightly infeasible variable fixings in
7417 presolving; reliable resactivities should make the BOUNDSCALETOL relaxation redundant.
7418 - removed `epsilontic` bug in cons_linear.c due to adjusting left/right hand side in applyfixing
7419 - fixed bug with multi-aggregated variables in cons_logicor: instead of fixing them, a linear constraint will be created
7420 - corrected bug in cons_linear.c:applyFixings() [if variable was fixed to infinity the rhs/lhs were wrong]
7421 - fixed bugs in pairwise presolving of cons_linear.c concerning deletion of upgraded constraints and inconsistent update
7422 of nchgsides in case of coefsequal and coefsnegated
7423 - fixed false assert and corrected a bug caused by deleting a constraint on `firstchanged` position in pairwise
7424 presolving with hashing in cons_linear.c
7425
7426- LP:
7427 - fixed handling of unbounded variables with 0 objective in SCIPlpGetModifiedPseudo[Proved]Objval() (lp.c)
7428 - fixed bug with uncatched LPSOLSTAT after hitting a time or iteration limit
7429 - corrected bug in SCIPlpGetState() if the LP is empty
7430 - fixed bug in SCIPlpSolveAndEval(): added extra simplex step if objlimit reached, fastmip and pricers enabled in order
7431 to get dual solution for pricing.
7432 - weakened two too strong asserts in lp.c concerning the LP result OBJLIMIT
7433 - fixed bug in SCIPlpSolveAndEval(): allow more than one extra simplex step for getting an objlimit exceeding solution
7434 with fastmip
7435
7436- Memory:
7437 - corrected invalid memory access in tcliqueIsEdge: added check whether node1 has no neighbors (tclique_graph.c)
7438 - removed memory leak detected with the help of coverity in dialog.c
7439 - fixed bug with memory reallocation in SCIPgetProbvarLinearSum()
7440 - tried to fix memory leak in dialog.c occuring from different versions of the readline/history libraries
7441 - removed possible memory leak in objdialog.cpp
7442
7443- Numerical:
7444 - fixed numerical issue in linear constraint propagation: need slightly more aggressive tightening such that probing
7445 does not choose a wrong value for fixing inside an epsilon interval
7446 - fixed numerical bug in dual presolving of linear constraint handler
7447 - avoid fixing variables to infinity in order to get rid of numerical inconsistencies in the original model
7448
7449- Objective:
7450 - added handling of the case of roundable variables with 0 objective in presol_dualfix.c
7451 - fixed bug with writing the MIP relaxation to a file concerning the objective function; in case the original objective
7452 function is requested, the transformed objective function gets re-transformed (scaling, offset)
7453 - fixed bug with wrong objective sense output for transformed problem. The transformed problem is always a minimization
7454 problem!
7455 - fixed bug with objective scaling after restart
7456
7457- Reading:
7458 - fixed bug with reading empty lines in TSP example
7459 - fixed bug with non-conformal parameter name in reader_ppm
7460 - fixed infinite loop in LP file reader if a line exceeds the character limit
7461 - fixed bug in reader_ppm while appending strings for output file
7462 - fixed some `SCIP_RETCODE` bugs in reader_fix.c, reader_sol.c, reader_sos.c and reader_zpl.c
7463 - fixed docu in type_reader.h
7464 - fixed bug with multi-aggregated variables which are de facto aggregated or fixed after flattening the aggregation tree
7465 - fixed bug with bound changes of variables in modifiable constraints during full dual presolving of linear conshdlr
7466 - increased compiler compatibility for C++ wrapper classed by adding extern `C` in obj*.cpp files and changing strlen
7467 calls to std::strlen
7468
7469- Separation:
7470 - corrected bug in priceAndCutLoop(): separation was aborted if domain reduction was applied
7471 - fixed bug in sepa_mir.c: size of testeddeltas-array was too small
7472 - corrected imlementation of SCIPlpiGetBasisInd() in lpi_clp.cpp (this fixes the bug that almost no Gomory cuts are
7473 found with Clp).
7474
7475- Sorting:
7476 - fixed bugs in sorttpl.c: fixed wrong arraysize in shellsort; in case an has at most one element, then no sorting is
7477 applied
7478 - fixed wrong if condition for function call in sorttpl.c
7479 - fixed obvious bug in linear constraint data sorting. Most part of the code assumed pure index sorting, but in fact, it
7480 was sorted by variable type as first criterion and index as second criterion.
7481
7482@page RN10 Release notes for SCIP 1.0
7483
7484@section RN100 SCIP 1.0.0
7485*************************
7486
7487Features
7488--------
7489
7490- SCIP now has a couple of specialized settings, all called scip_*.set
7491- SCIP is now compatible to the Exception branch of SoPlex
7492- if possible, objective function is scaled to make objective value integral with gcd 1
7493- slightly modified automatic constraint aging strategy
7494- new C templates disp_xxx.h and dialog_xxx.h and C++ wrapper classes objdisp.h and objdialog.h, respectively
7495- modified reader `sol`, st. files which where created via typing the order of commands `set log *.sol`,
7496 `disp sol var -`, `set log cplex.log` in Cplex can now be read
7497- new dummy LP interface `lpi_none.c`; useful for running SCIP without a LP solver
7498
7499- Presolver:
7500 - modified probing presolver to do multiple cycles if called in subsequent runs
7501 - changed sort algorithm in probing presolver
7502
7503- Node selection:
7504 - new node selection rule `estimate` (best estimate search)
7505 - new node selection rule `hybridestim`
7506
7507- Documentation:
7508 - the doxygen documentation now has HowTo's for all plugin types
7509 - the doxygen documentation now contains a FAQ
7510 - the documentation has now a TAB Modules; there you can find list of available constraint handles, presolvers,
7511 propagators, lpi interfaces, file readers and so on
7512
7513- Time:
7514 - time limit is now forwarded to lp solving algorithm
7515 - presolving, cut separation, primal heuristics and strong branching now better respect time limit
7516
7517- Heuristics:
7518 - best estimate search is now used in all large neighborhood search heuristics
7519 - new improvement heuristic `oneopt`
7520 - new heuristic `actconsdiving` following an idea of John Chinneck
7521
7522- Separation and Cuts:
7523 - modified cut selection code
7524 - cut conversion into linear constraints after a restart now works better
7525 - added flow cover separator
7526 - gomory cuts are now also separated for integral slack variables
7527 - less aggressive in Gomory cut separation
7528 - strong CG cuts are now also separated for integral slack variables
7529
7530Performance improvements
7531------------------------
7532
7533- greatly improved performance of LP file reader by replacing string copies with pointer copies
7534- removed performance bottleneck with non-bfs based node selectors and large leaf queues at the cost of a small memory
7535 overhead (2 ints per node in the leaf queue); this improves performance quite a bit on instances that take a large
7536 number of branching nodes
7537- improved performance of linear constraint propagation by delaying some floor/ceil calculations
7538- improved performance of clique cut separator
7539
7540Interface changes
7541-----------------
7542
7543### New and changed callbacks
7544
7545- new callback method SCIPdialogFree()
7546
7547### Deleted and changed API methods
7548
7549- slightly modified bound substitution heuristic in SCIPcalcMIR() and SCIPcalcStrongCG()
7550- slightly less conservative in numerics for SCIPmakeRowIntegral()
7551- linear and knapsack constraint handler may now deal with coefficients of value zero
7552- new parameter `maxbounddist` for SCIPincludeSepa() and constructor ObjSepa()
7553- new parameter `restart` for method SCIPfreeSolve()
7554- calling SCIPwriteLP() is now possible in Solved Stage
7555- SCIPwrite{LP,MIP} may no longer be called after solving, since the LP data structures may not be valid
7556- All functions SCIP<datatype>Param() got a new parameter `isadvanced`.
7557 This does not influence the performance of SCIP, but the position of the parameter in the settings menu.
7558 Hence, if you do not care about this, you can assign any value to it.
7559 You should add the corresponding flag to the SCIP<datatype>Param() calls in your own source code.
7560
7561- Version:
7562 - modified `SCIP_SUBVERSION` to be a number instead of a string (to be able to use `SCIP_SUBVERSION >= ...`)
7563 - SCIPsubversion() now returns an int instead of a const char*
7564
7565- Tree and Nodes:
7566 - new parameter `estimate` for SCIPcreateChild() giving an estimate for value of best feasible solution in the subtree to
7567 be created. One possibility is to use SCIPgetLocalOrigEstimate() for this value.
7568 - removed method SCIPnodeGetPriority()
7569 - removed parameter `lowestboundfirst` from SCIPincludeNodesel()
7570
7571- Branching:
7572 - removed parameter `branchdir` from SCIPbranchVar()
7573 - new parameters `leftchild`, `eqchild` and `downchild` for SCIPbranchVar()
7574 - SCIPgetVarStrongbranch() now also returns lperror == TRUE if the solving process should be stopped, e.g., because of a
7575 time limit
7576
7577- Variable tightening:
7578 - replaced methods SCIPvarGetClosestVlb() and SCIPvarGetClosestVub() from pub_var.h by new methods
7579 SCIPgetVarClosestVlb() and SCIPgetVarClosestVlb() in scip.h
7580 - new parameter `force` for SCIPtightenVarLb() and SCIPtightenVarUb()
7581
7582### New API functions
7583
7584- SCIPreadSol()
7585- SCIPwriteMIP()
7586- SCIPgetLocalOrigEstimate() and SCIPgetLocalTransEstimate()
7587- SCIPisStopped()
7588- SCIProwIsInGlobalCutpool()
7589- SCIPresetParams()
7590- SCIPgetVarRedcost()
7591- SCIPtightenVarLbGlobal() and SCIPtightenVarUbGlobal()
7592- SCIPsepaGetMaxbounddist()
7593- SCIPboundchgGetNewbound(), SCIPboundchgGetVar(), SCIPboundchgGetBoundchgtype(),
7594 SCIPboundchgGetBoundtype(), SCIPboundchgIsRedundant(), SCIPdomchgGetNBoundchgs(), SCIPdomchgGetBoundchg()
7595- SCIPnodeUpdateLowerboundLP()
7596- SCIPcalcNodeselPriority()
7597- SCIPnodeGetEstimate()
7598- SCIPnodeGetDomchg()
7599- SCIPgetRootNode() (in combination with SCIPcutoffNode(), this allows the immediate finishing of the optimization)
7600
7601### Command line interface
7602
7603- default dialog menu now includes the commands `set default` and `display parameters`
7604- added option to write node LP and MIP relaxations to LP file from interactive shell
7605
7606### Changed parameters
7607
7608- parameters are now separated into basic and advanced, the latter ones have been moved to extra submenus
7609- priority parameters are now restricted to be in [INT_MIN/4,INT_MAX/4] to avoid overflow errors in comparison methods
7610- increased priority of `estimate` node selector, such that this is the new default node selector
7611- changed meaning of parameter setting `nodeselection/childsel = l`; old meaning is now called `r`
7612- changed default value of `conflict/maxvarsfac` to 0.1
7613- changed default value of `conflict/useprop` to TRUE
7614- changed default value of `conflict/useinflp` to TRUE
7615- changed default value of `conflict/usepseudo` to TRUE
7616- changed default value of `conflict/maxlploops` to 2
7617- changed default value of `conflict/lpiterations` to 10
7618- changed default value of `conflict/interconss` to -1
7619- changed default value of `conflict/reconvlevels` to -1
7620- changed default value of `conflict/settlelocal` to FALSE
7621- changed default value of `constraints/linear/propfreq` to 1
7622- changed default values of `heuristics/∗diving/backtrack` to TRUE
7623- changed default value of `nodeselection/restartdfs/stdpriority` to 10000
7624- changed default value of `numerics/boundstreps` to 0.05 in order to avoid very long propagation loops on continuous variables
7625- changed default value of `presolving/restartfac` to 0.05
7626- changed default value of `presolving/restartminred` to 0.10
7627- changed default value of `separating/objparalfac` to 0.01 for performance reasons
7628- changed default value of global `separating/maxbounddist` to 1.0
7629- changed default value of `separating/objparalfac` to 0.0001
7630
7631### New parameters
7632
7633- `conflict/enable` to globally enable or disable conflict analysis
7634- `constraints/linear/maxcardbounddist` and `constraints/knapsack/maxcardbounddist`
7635- `heuristics/∗diving/backtrack` to activate 1-level backtracking for most of the diving heuristics
7636- `heuristics/feaspump/maxstallloops`
7637- `nodeselection/childsel` to control the child selection
7638- `presolving/immrestartfac`
7639- `separating/∗/maxbounddist` to have individual maxbounddist parameters per separator
7640- `separating/clique/backtrackfreq` to speed up clique cut separation in heuristic fashion
7641- `separating/redcost/continuous`
7642
7643Build system
7644------------
7645
7646### Makefile
7647
7648- added version numbers to library files (There will be a softlink generated in the lib/ and bin/ directories without
7649 version number that point to the latest compiled version.)
7650- added .exe extension to binaries of MinGW
7651- removed the `.static` extension associated to the LINK variable from the Makefile system (If you want to build
7652 makefiles for shared library generation, use the OPT variable. For example, you could create a makefile
7653 `make/make.linux.x86.gnu.opt-shared` and compile it with `make OPT=opt-shared`.)
7654
7655- Defaults and Options:
7656 - modified the default LP solver to be SoPlex instead of CPLEX
7657 - added `LPS=none` for compiling SCIP without a LP solver
7658 - made `ZIMPL=true` the default; if you do not want to include ZIMPL support, call `make ZIMPL=false`
7659
7660Fixed bugs
7661----------
7662
7663- fixed bug in rowScale() concerning deletion of almost zero coefficients
7664- weakened assert in primal.c in order to avoid numerical troubles
7665- fixed bug with too long variable names
7666- fixed bug with strange user descriptions of plugins
7667- changed position of some asserts to prevent segmentation faults
7668- SCIPgetAvgPseudocostCount() and SCIPgetAvgPseudocostCountCurrentRun() now return the average over all integer
7669 variables instead of all variables, since pseudo costs are not recorded for continuous variables
7670- fixed wrong sorting of plugins with priorities close to INT_MIN or INT_MAX
7671- replaced `line` by `read` in Makefile, since `line` is non-standard
7672- fixed bug with branching rules that produce only one child with no changes to the problem
7673- fixed bug that external relaxator is not reset appropriately for a new problem instance
7674- removed wrong assert in function paramWrite()
7675- fixed bug with uninitialized in check.awk
7676- fixed bug in ZIMPL file reader for multiple occurrences of a single variable in the objective function
7677- fixed bug with deleting variables from the transformed problem that are contained in the implication graph
7678- fixed bug in root reduced cost fixing propagator that leads to an empty domain for a variable as a proof of optimality
7679 of the current incumbent
7680- fixed bug with fractional coefficients of binary variables in cont --> impl int upgrading
7681
7682- Solution:
7683 - fixed bug with aggregated variables in debug solution test
7684 - now it is possible to add original solutions
7685 - fixed bugs with SCIPgetBestsol() returning `NULL` after a restart with user objective limit
7686 - fixed wrong status code in presence of user objective limit and a feasible solution that is not better than the limit
7687
7688- Bounds:
7689 - fixed bug with wrong bound changes of loose variables
7690 - changed wrong assert in SCIPnodeAddBoundinfer()
7691 - fixed bug in variable bounds search and insertion method
7692 - fixed bug regarding modifying bounds in original problem if negated original variables exist
7693 - fixed bug with multiple pending bound changes on some variable
7694
7695- Separator:
7696 - fixed bug in integer objective separator with restarts
7697 - fixed bug in integer objective separator with dynamic columns
7698
7699- Cuts:
7700 - fixed bug that cut age was not reset to zero for violated cuts
7701 - fixed bug in SCIPcutpoolAddNewRow() concerning update of minidx and maxidx of added row
7702 - fixed numerical bug in rowScaling of lp.c, which possibly cut off feasible solutions
7703 - significantly improved performance of c-MIR and Gomory cuts by caching closest VLB and VUB info
7704
7705- LP:
7706 - fixed numerical buf with slightly different LP optimum after resolving due to probing/diving
7707 - fixed bug in cmir and flowcover separator with variables which are currently not in the LP
7708 - fixed bug with LP size management in probing if column generation is used
7709 - fixed bug in LP file reader with row names identical to section keywords
7710 - fixed potential bugs due to errors in resolving the LP after diving or probing
7711 - fixed potential bugs in SCIPpriceLoop() and priceAndCutLoop(), st. now all LP solution stati are handled appropriately
7712 - fixed potential bug with non-existent LP in SCIPwrite{LP,MIP}
7713
7714- Constraint handler:
7715 - removed wrong assert in bounddisjunction constraint enforcement
7716 - fixed numerical bug in propagator of varbound constraint handler
7717 - fixed bug in variable bound constraint handler with changing bounds on multi-aggregated variables
7718 - fixed bug in linear constraint handler: only tight cuts are transformed into linear constraints after restart
7719 - fixed bug in bounddisjunction constraint handler with propagation of multi-aggregated variables
7720 - fixed bug with numerics in linear constraint handler due to non-representable `BOUNDSCALETOL`
7721 - fixed bug with almost integral multi-aggregation in dual presolve of linear constraint handler
7722 - fixed bug with numerics in update of min/maxactivity in linear constraint handler
7723
7724- Heuristics:
7725 - fixed bug in intshifting and oneopt heuristic with variables which are currently not in the LP
7726 - fixed bug with primal heuristics reducing the cutoff bound such that the current node is cut off
7727 - fixed bug in oneopt heuristic: must not be called on pseudo nodes if continuous variables are present
7728
7729@page RN09 Release notes for SCIP 0.9
7730
7731@section RN090 SCIP 0.9.0
7732*************************
7733
7734Features
7735--------
7736
7737- the EXITSOL callback of the plugins is now called before the LP and the global cut pool are freed
7738
7739- Primal Heuristics:
7740 - new primal heuristics `rens`, `mutation` and `veclendiving`
7741 - primal heuristics that run before the node is solved now know already whether the LP will be solved at the current
7742 node or not
7743
7744- Heuristics:
7745 - new heuristic `intshifting` (ID character `i`)
7746 - in the root node of the very first run, heuristics with timing `AFTERNODELPNODE`, `AFTERLPPLUNGE`, `AFTERPSEUDONODE`, and
7747 `AFTERPSEUDOPLUNGE` are now called before the enforcement of the constraint handlers, in particular before the branching
7748 rules; in this way, the branching rule can already benefit from a tighter primal bound
7749 - if a heuristic found a better solution after the LP loop (and in particular the `AFTERNODE` heuristics in the root node
7750 of the very first run, see above), domain propagation and LP solving is triggered again; this allows for additional
7751 reduced cost tightening and other dual propagations
7752 - slightly modified `crossover` and `rins` heuristics
7753 - improved performance of intdiving heuristic
7754 - improved heuristic `octane` and `shifting`
7755 - slightly modified rens and localbranching heuristics
7756 - modified guided diving heuristic such that it equals the original version of the heuristic (i.e., round in direction of the
7757 current incumbent solution instead of the average of all primal feasible solutions)
7758 - ID character for intdiving heuristic is now `I`
7759
7760- Separation and Cuts:
7761 - c-MIR cuts try now to scale the cut to integral values; however, cuts are still generated if this fails
7762 - hard-coded relative objective gain to consider a separation loop to be stalling is now changed from 1e-3 to 1e-4,
7763 which means that separation is not aborted as early as before
7764 - modified c-MIR cut separator to more closely resemble the original version of Marchand and Wolsey
7765
7766- Constraint:
7767 - possibility of SAT-like restarts after a number of conflict constraints have been found
7768 - improved presolving of and, or and xor constraints
7769 - implemented additional dual presolving in linear constraint handler
7770 - slightly modified presolving of varbound constraint handler
7771
7772Interface changes
7773-----------------
7774
7775### New and changed callbacks
7776
7777- new parameter `solinfeasible` for constraint handler callback methods `ENFOLP` and `ENFOPS`
7778- replaced callback parameter `inlploop` and `inplunging` by `heurtiming` in `SCIP_DECL_HEUREXEC`
7779- slightly changed the meaning of the result codes returned by external relaxators: if they modify the LP or tighten
7780 bounds of variables, they are not automatically be called again (it is assumed that they already made use of these
7781 changes). They are only called again, if they returned `SCIP_SUSPENDED` or if some other plugin modified the LP.
7782
7783### Deleted and changed API methods
7784
7785- new parameter `escapecommand` for SCIPdialoghdlrAddHistory()
7786- removed method SCIPgetVarData(); use SCIPvarGetData() from pub_var.h instead
7787- new calls SCIPgetLPBInvCol() and SCIPgetLPBInvACol() to access the basis inverse and simplex tableau columnwise
7788- new parameter `ndomredsfound` of SCIPpropagateProbing()
7789- new parameters `fixintegralrhs`, `maxfrac`, `mksetcoefs` and `fracnotinrange` in SCIPcalcMIR()
7790- modified SCIPfixVar() such that in problem creation stage it will change the bounds as requested even if the fixing
7791 value is outside of the current bounds
7792- replaced parameters `pseudonodes`, `duringplunging`, `duringlploop` and `afternode` by `timingmask` in
7793 SCIPincludeHeur() and constructor of ObjHeur() class use the following table to translate old settings into the new
7794 timingmask:
7795
7796| PSEUDONODES | DURINGPLUNGING | DURINGLPLOOP | AFTERNODE | timingmask |
7797|-------------|----------------|--------------|-----------|---------------------------------------------------------------|
7798| FALSE | FALSE | FALSE | FALSE | SCIP_HEURTIMING_BEFORENODE |
7799| TRUE | FALSE | FALSE | FALSE | SCIP_HEURTIMING_BEFORENODE |
7800| FALSE | TRUE | FALSE | FALSE | SCIP_HEURTIMING_BEFORENODE |
7801| TRUE | TRUE | FALSE | FALSE | SCIP_HEURTIMING_BEFORENODE |
7802| FALSE | FALSE | TRUE | FALSE | SCIP_HEURTIMING_BEFORENODE \| SCIP_HEURTIMING_DURINGLPLOOP |
7803| TRUE | FALSE | TRUE | FALSE | SCIP_HEURTIMING_BEFORENODE \| SCIP_HEURTIMING_DURINGLPLOOP |
7804| FALSE | TRUE | TRUE | FALSE | SCIP_HEURTIMING_BEFORENODE \| SCIP_HEURTIMING_DURINGLPLOOP |
7805| TRUE | TRUE | TRUE | FALSE | SCIP_HEURTIMING_BEFORENODE \| SCIP_HEURTIMING_DURINGLPLOOP |
7806| FALSE | FALSE | FALSE | TRUE | SCIP_HEURTIMING_AFTERLPPLUNGE |
7807| TRUE | FALSE | FALSE | TRUE | SCIP_HEURTIMING_AFTERPLUNGE |
7808| FALSE | TRUE | FALSE | TRUE | SCIP_HEURTIMING_AFTERLPNODE |
7809| TRUE | TRUE | FALSE | TRUE | SCIP_HEURTIMING_AFTERNODE |
7810| FALSE | FALSE | TRUE | TRUE | SCIP_HEURTIMING_AFTERLPPLUNGE \| SCIP_HEURTIMING_DURINGLPLOOP |
7811| TRUE | FALSE | TRUE | TRUE | SCIP_HEURTIMING_AFTERPLUNGE \| SCIP_HEURTIMING_DURINGLPLOOP |
7812| FALSE | TRUE | TRUE | TRUE | SCIP_HEURTIMING_AFTERLPNODE \| SCIP_HEURTIMING_DURINGLPLOOP |
7813| TRUE | TRUE | TRUE | TRUE | SCIP_HEURTIMING_AFTERNODE \| SCIP_HEURTIMING_DURINGLPLOOP |
7814
7815- Constraints:
7816 - renamed all occurences of `removeable` by the correct English word `removable`: SCIPconsIsRemovable(),
7817 SCIPsetConsRemovable(), SCIPvarIsRemovable(), SCIPcolIsRemovable(), SCIProwIsRemovable()
7818 - new parameter `sticktonode` in SCIPcreateCons(), SCIPcreateConsAnd(), SCIPcreateConsBounddisjunction(),
7819 SCIPcreateConsKnapsack(), SCIPcreateConsLinear(), SCIPcreateConsLogicor(), SCIPcreateConsOr(),
7820 SCIPcreateConsVarbound(), SCIPcreateConsXor(), SCIPcreateConsSetpart(), SCIPcreateConsSetpack(),
7821 SCIPcreateConsSetcover(): usually, you should set this to FALSE; if you want to add constraints as node markers with
7822 node data and, e.g., use the `activate` and `deactivate` callbacks to get informed about the activation and
7823 deactivation of the node, you should set this flag to TRUE in order to make sure, that the constraint will always be
7824 associated to the node and not moved to a more global node if this would be possible
7825 - slightly changed semantics of SCIPaddConsNode() and SCIPaddConsLocal(), such that a constraint which is added to the
7826 root node now enters the global problem (and is still existing after a restart)
7827
7828### New API functions
7829
7830- SCIPgetVerbLevel()
7831- SCIPescapeString()
7832- SCIPgetGlobalCutpool(), SCIPgetPoolCuts(), SCIPcutpoolGetCuts(), SCIPcutGetRow() and SCIPcutGetAge()
7833- SCIPconsGetNLocksPos() and SCIPconsGetNLocksNeg()
7834
7835### Command line interface
7836
7837- command shell now understands escape characters `\``,`'` and `\` which makes it possible to read in files with spaces in the
7838 name
7839
7840### Interfaces to external software
7841
7842- updated XPress interface to XPress-MP 17 (contributed by Michael Perregaard)
7843
7844### Changed parameters
7845
7846- changed default value of `heuristics/octane/usediffray` to FALSE
7847- removed parameter `heuristics/octane/usediffbwray`
7848- renamed parameter `heuristics/octane/useavgray` to `heuristics/octane/useavgnbray`
7849- changed default value of `heuristics/rens/binarybounds` to TRUE
7850- changed default value of `heuristics/octane/freq` to -1 in order to deactivate Octane
7851- parameter `heuristics/feaspump/maxsols` is now strict, i.e., if n solutions were already found, the feasibility pump
7852 starts to work only if `maxsols <= n`, instead of `maxsols < n`
7853
7854### New parameters
7855
7856- `conflict/restartnum` and `conflict/restartfac`
7857- `heuristics/octane/useavgray`
7858- `heuristics/octane/useavgwgtray`
7859- `limits/absgap` to define an absolute gap limit
7860- `separating/cmir/aggrtol`
7861- `separating/cmir/densityscore`
7862- `separating/cmir/fixintegralrhs`
7863- `separating/maxruns`
7864- `presolving/restartminred` which forbids another restart if the last one was not successful enough
7865- `propagating/abortoncutoff`
7866- `reading/zplreader/changedir` to control behavior of path switching of ZIMPL file reader
7867- `reading/zplreader/parameters` to pass additional parameters to ZIMPL
7868
7869Build system
7870------------
7871
7872### Makefile
7873
7874- added ncurses to the readline entries in the `make/make.*` files
7875- added quotes to sed expressions in Makefile (needed under Windows)
7876- modified makefiles for Windows/Intel
7877- added automatic query script in the Makefile for soft-link names
7878
7879Fixed bugs
7880----------
7881
7882- fixed bug with string pointer copy instead of string content duplication in constructors of C++ wrapper classes
7883- fixed bug in CPLEX interface with basis access methods that dualopt has to be called for more error status codes
7884- fixed bug with inserting two variable bounds of the same type on the same variable with the same bounding variable but
7885 with different sign of coefficient (e.g., `x <= 10*z + 5` and `x <= -5*z + 10`); in previous version, one of the two was
7886 removed, although both have a useful meaning; now, we keep both and detect a stronger global bound in the implication graph presolving
7887- objective function is now also checked for integrality after problem transformation (fixed a bug that a solution which
7888 was generated between transformation and presolving for an integral objective function did not reduce the cutoff bound by one)
7889- fixed a bug with cmir cut efficacy calculation (however, on my first tests, the performance reduced slightly!)
7890- fixed bug that SCIPvarGetAvgSol() always returned the upper bound (affected guided diving heuristic)
7891- fixed bug in RENS, RINS, Local Branching, Crossover and Mutation heuristics with wrong variable-subvariable assignments
7892- fixed bug in infeasible/bound-exceeding LP conflict analysis if the bounds were relaxed in diving (happens in intshifting heuristic)
7893
7894- Separation:
7895 - fixed bug with adding constraints with `INITIAL=true` and separating them afterwards, which lead to a second addition of
7896 the constraint's relaxation in the child node
7897 - separation LPs are now immediately resolved after a bound change was generated by a cut separator; before, the
7898 separation round was prematurely aborted, which means that a separation round limit was sometimes reached very quickly
7899 and some of the separators were not even called a single time
7900
7901- Cmir Cut Separator:
7902 - too large deltas are now also rejected in c-MIR cut separation
7903 - fixed bug in cmir cut separator, that 8*delta was not tried
7904 - fixed bug in cmir cut separator with wrong sign of slack in row score function
7905 - fixed bug in cmir cut separator with weights fixed to zero, thus making the current aggregation invalid
7906 - fixed bug in cmir cut separator with wrong calculation of cut efficacies
7907
7908@page RN08 Release notes for SCIP 0.8
7909
7910@section RN082 SCIP 0.8.2
7911*************************
7912
7913Features
7914--------
7915
7916- additional flag `delay` for pricers
7917- new propagator `rootredcost` which applies reduced cost fixing at the root node whenever a best new primal solution was found
7918- new separator `redcost` which replaces the internal reduced cost strengthening
7919
7920- LP:
7921 - extensions to the LP are kept even if the LP is not solved at the current node; however, if the LP turned out to be
7922 numerically instable, the extensions of the current node are still discarded
7923 - added removal of bound-redundant rows from the LP during root node LP solving loop
7924 - new display column `lpobj`
7925
7926- Constraints:
7927 - slightly changed priorities of constraint handlers
7928 - now, conflict constraints are also created if they were generated in strong branching or diving with insertion depth
7929 equal to the current depth
7930 - new constraint handler `bounddisjunction`
7931
7932- Readers:
7933 - renamed `sol` file reader to `fix` file reader (reads partial solution files and fixes variables to the given values)
7934 - added `sol` file reader which reads complete solution files and adds the solutions to the solution pool
7935 - LP and MPS file readers are now able to parse lazy constraints and user cuts sections
7936
7937- Presolver:
7938 - knapsack presolver now generates cliques in the clique table (this essentially solves `neos1.mps`)
7939 - new presolver `inttobinary`
7940
7941- Heuristics:
7942 - new primal heuristic `shifting`
7943 - diving heuristics abort earlier (did not come back in reasonable time on `fast0507`)
7944
7945Interface changes
7946-----------------
7947
7948- new solution status code `SCIP_STATUS_STALLNODELIMIT`
7949
7950### New and changed callbacks
7951
7952- slightly modified semantics of the `CONSINITLP` callback in the constraint handlers
7953
7954### Deleted and changed API methods
7955
7956- methods SCIPisLbBetter() and SCIPisUbBetter() have an additional parameter and slightly different meaning (they now
7957 compare the bound improvement *relatively* to the width of the domain and the bound itself)
7958- SCIPgetNSols() now returns an int instead of `SCIP_Longint`
7959- method SCIPreadProb() does not call SCIPfreeTransform() anymore; file readers that want to extend the existing problem
7960 must now call SCIPfreeTransform() themselves before modifying the original problem
7961- method SCIPgetBinvarRepresentative() can now also be called in problem creation stage
7962- additional parameter `maxpricerounds` in method SCIPsolveProbingLPWithPricing()
7963- changed name of method SCIPpresolGetNVarTypes() to SCIPpresolGetNChgVarTypes()
7964- method SCIPsplitFilenames() now treats both versions of slashes, `/` and `\`, as directory delimiters (under MinGW and
7965 CygWin, both are valid; so, we cannot treat file names anymore where the other slash is used as a regular character)
7966
7967- Constraints:
7968 - marking a constraint to be `initial` now means in addition, that if the constraint is added to a local node it will
7969 enter the LP at the time the node is first processed, even if parameters forbid separation at this node
7970 - changed name of method SCIPconshdlrGetNVarTypes() to SCIPconshdlrGetNChgVarTypes()
7971
7972- Conflicts:
7973 - method SCIPgetNConflictClausesFound() renamed to SCIPgetNConflictConssFound()
7974 - method SCIPgetNConflictClausesFoundNode() renamed to SCIPgetNConflictConssFoundNode()
7975 - method SCIPgetNConflictClausesApplied() renamed to SCIPgetNConflictConssApplied()
7976
7977### New API functions
7978
7979- SCIPsolveProbingLPWithPricing()
7980- SCIPchgVarLbRoot() and SCIPchgVarUbRoot()
7981- SCIPinRepropagation()
7982- SCIPaddDialogInputLine() and SCIPaddDialogHistoryLine()
7983- SCIPtransformProb() to create the transformed problem; enables the user, e.g., to add primal solutions before the presolving begins
7984- SCIPcreateSolCopy()
7985- SCIPareSolsEqual()
7986
7987- Getters:
7988 - SCIPgetRowKnapsack(), SCIPgetRowLinear(), SCIPgetRowLogicor(), SCIPgetRowSetppc(), and
7989 SCIPgetRowVarbound() for obtaining the linear relaxation of a corresponding constraint
7990 - SCIPgetLhsVarbound(), SCIPgetRhsVarbound(), SCIPgetVarVarbound(), SCIPgetVbdvarVarbound(), and
7991 SCIPgetVbdcoefVarbound()
7992 - SCIPgetLPRootObjval(), SCIPgetLPRootColumnObjval() and SCIPgetLPRootLooseObjval()
7993 - SCIPcolGetMinPrimsol() and SCIPcolGetMaxPrimsol()
7994 - SCIPgetFocusDepth()
7995
7996- Score:
7997 - SCIPgetAvgPseudocostScore()
7998 - SCIPgetAvgPseudocostScoreCurrentRun()
7999 - SCIPgetAvgConflictScore()
8000 - SCIPgetAvgConflictScoreCurrentRun()
8001 - SCIPgetAvgInferenceScore()
8002 - SCIPgetAvgInferenceScoreCurrentRun()
8003 - SCIPgetAvgCutoffScore()
8004 - SCIPgetAvgCutoffScoreCurrentRun()
8005
8006- Reduced Cost:
8007 - SCIPgetColRedcost()
8008 - SCIPvarGetRootRedcost()
8009
8010- Variables:
8011 - SCIPgetNVarsAnd() and SCIPgetVarsAnd()
8012 - SCIPgetWeightsKnapsack(), SCIPgetNVarsKnapsack(), SCIPgetVarsKnapsack() and SCIPgetWeightsKnapsack()
8013 - SCIPgetNVarsLinear(), SCIPgetVarsLinear() and SCIPgetValsLinear()
8014 - SCIPgetNVarsOr() and SCIPgetVarsOr()
8015 - SCIPgetNVarsXor() and SCIPgetVarsXor()
8016
8017### Command line interface
8018
8019- command line syntax changed to support batch modus without piping stdin with `<` or `|` operators
8020- advanced command line syntax:
8021 - `-l <logfile> `: copy output into log file
8022 - `-q `: suppress screen messages
8023 - `-s <settings> `: load parameter settings (.set) file
8024 - `-f <problem> `: load and solve problem file
8025 - `-b <batchfile>`: load and execute dialog command batch file (can be used multiple times)
8026 - `-c <command> `: execute single line of dialog commands (can be used multiple times)
8027
8028### Interfaces to external software
8029
8030### Changed parameters
8031
8032- removed parameter `propagating/redcostfreq`, because reduced cost strengthening is now an external separator plugin
8033- removed parameter `conflict/maxunfixed`
8034- parameter `conflict/maxclauses` renamed to `conflict/maxconss`
8035- parameter `conflict/interclauses` renamed to `conflict/interconss`
8036- parameter `conflict/reconvclauses` replaced by `conflict/reconvlevels`
8037- parameter `conflict/uselp` replaced by `conflict/useinflp` and `conflict/useboundlp`
8038- changed default value of `constraints/obsoleteage` to -1
8039- changed default value of `branching/relpscost/conflictweight` to 0.01
8040- changed default value of `branching/relpscost/inferenceweight` to 0.0001
8041- changed default value of `branching/relpscost/cutoffweight` to 0.0001
8042- in bfs node selector, parameter `minplungedepth` is now stronger than `maxplungedepth` if they conflict
8043
8044### New parameters
8045
8046- `constraints/linear/separateall`
8047- `conflict/lpiterations`
8048- `conflict/keepreprop`
8049- `branching/relpscost/conflictweight`, `branching/relpscost/inferenceweight`,
8050 `branching/relpscost/cutoffweight` and `branching/relpscost/pscostweight`
8051- `conflict/settlelocal`
8052- `conflict/depthscorefac`
8053- `limits/stallnodes`
8054
8055Build system
8056------------
8057
8058### Makefile
8059
8060- removed ncurses and pthread libraries from the Makefile; pthread is now only linked if CPLEX is used
8061
8062Fixed bugs
8063----------
8064
8065- fixed numerical bug in SCIPrealToRational() [thanks to Anders Schack-Nielsen]
8066- fixed bug in crossover heuristic with negative timelimit
8067- removed bug in conflict analysis with wrong redundancy check
8068- fixed bug that unexpected end of stdin (Ctrl-D or piped-in file without `quit` command) gives a segmentation fault
8069- fixed bug with inconsistent data structures after a global bound was changed at a local subproblem and the local
8070 bounds are not contained anymore in the new global bounds
8071- fixed dependency generation in example Makefiles
8072
8073- Knapsack:
8074 - fixed bug in knapsack presolving with redundancy check after applyFixings() [thanks to Anders Schack-Nielsen]
8075 - fixed bug in knapsack separator with empty initial covers
8076 - fixed bug in knapsack constraint disaggregation that may lead to acceptance of infeasible solutions
8077 - fixed bug in knapsack constraint handler where a modifiable constraint may be declared redundant
8078
8079- LP:
8080 - fixed bug with missing LP size updates after pricing or cut separation in probing [thanks to Marc Nuenkesser]
8081 - fixed bug in CPLEX interface with getting basis information after the LP was modified and restored
8082 - fixed bug with updating LP size in probing
8083 - fixed bug that SCIPgetLPSolstat() returns a valid status code even if the LP was not yet constructed for the current node
8084
8085- Variables:
8086 - fixed bug with invalid lazy updates after a restart where the LP is not solved again (e.g., due to all variables being fixed)
8087 - fixed bugs resulting from inactive general integer variables being member of the variable bounds array of a variable
8088 - fixed bug in updatePseudocost() with wrong lpgain distribution on multiple branching variables [thanks to Anders Schack-Nielsen]
8089 - fixed bug in objconshdlr.h where member variable scip_maxprerounds_ was declared as an `SCIP_Bool` instead of an int
8090 - branching on nearly-integral variables is now avoided in relpscost branching, which lead to a numerical assertion
8091
8092- Implication:
8093 - fixed bug with adding implications that fix the implication variable to the opposite value (due to the bug, it was
8094 returned that the whole problem is infeasible)
8095 - removed wrong assert in varRemoveImplicsVbs()
8096
8097- Cliques:
8098 - fixed bug in SCIPcliqueSearchVar() [thanks to Anders Schack-Nielsen]
8099 - fixed bug in SCIPcliqueAddVar() [thanks to Anders Schack-Nielsen]
8100
8101- Readers:
8102 - fixed bug in MPS file reader with `OBJSENSE`
8103 - fixed bug in LP reader with potentially uninitialized pointers [thanks to Martin Mueller]
8104
8105- Constraints:
8106 - it is now possible to branch on constraints without the risk of going into an infinite loop, because constraints marked as `initial`
8107 will be put to the LP relaxation (of the child nodes) even if separation is prohibited by the parameter settings
8108 - fixed bug that locally valid varbound constraints produce VLB/VUB entries [thanks to Anders Schack-Nielsen]
8109
8110@section RN081 SCIP 0.8.1
8111*************************
8112
8113Features
8114--------
8115
8116- improved performance of the priority queue in conflict analysis
8117- slightly modified restartdfs node selector
8118
8119- Presolving:
8120 - new presolver `implics` to find bound changes and aggregations out of the implication graph
8121 - modified probing order in probing presolver
8122
8123- Constraints:
8124 - changed handling of added constraints in separation calls
8125 - modified bookkeeping of locally added and disabled constraints such that the order of enabling and disabling constraints stays the same
8126 - logic or constraint handler now adds implications on clauses with 2 literals to the implication graph
8127 - and/or constraint handlers now add implications to the implication graph
8128 - xor constraint handler now uses stronger LP relaxation without auxiliary variable for xor constraint with 2 operands
8129
8130- Heuristics:
8131 - added preliminary version of `intdiving` heuristic (disabled in default settings)
8132 - added crossover heuristic
8133
8134- Readers:
8135 - LP file reader now accepts the keyword `Integer` for defining the start of the integer variables section
8136 - new file reader for (partial) solutions
8137
8138Examples and applications
8139-------------------------
8140
8141- added two small pricer examples (for C and C++)
8142- updated example code (s.t. it compiles again)
8143
8144Interface changes
8145-----------------
8146
8147### New and changed callbacks
8148
8149- callback method `CONSSEPA` of constraint handler was split into two methods `CONSSEPALP` and `CONSSEPASOL`
8150- callback method `SEPAEXEC` of separator was split into two methods `SEPAEXECLP` and `SEPAEXECSOL`
8151
8152### Deleted and changed API methods
8153
8154- replaced method SCIPsepaWasDelayed() by SCIPsepaWasLPDelayed() and SCIPsepaWasSolDelayed()
8155- additional parameter `sol` for methods SCIPaddCut(), SCIPgetCutEfficacy() and SCIPisCutEfficacious()
8156- additional parameter `sol` for method SCIPseparateKnapsackCover()
8157- primal solutions may now contain values marked to be unknown (value is `SCIP_UNKNOWN`); unknown values don't contribute
8158 to the objective value of the solution; an unknown solution value should be treated as an arbitrary value in the
8159 variable's bounds, e.g., in the calculation of the feasibility of a constraint, a value inside the variable's bounds
8160 should be selected that makes the constraint as feasible as possible
8161- new parameter `printzeros` for methods SCIPprintSol(), SCIPprintTransSol(), SCIPprintBestSol() and SCIPprintBestTransSol()
8162
8163- Constraints:
8164 - replaced method SCIPconshdlrWasSeparationDelayed() by two methods SCIPconshdlrWasLPSeparationDelayed() and
8165 SCIPconshdlrWasSolSeparationDelayed()
8166 - renamed method SCIPgetNGlobalConss() to SCIPgetNConss()
8167
8168### New API functions
8169
8170- SCIPgetCuts()
8171- SCIPgetVarConflictScore() and SCIPgetVarConflictScoreCurrentRun()
8172- SCIPvarSetData()
8173- SCIPcreateUnknownSol()
8174- SCIPgetNConflictClausesFoundNode()
8175- SCIPvarSetDelorigData(), SCIPvarSetTransData() and SCIPvarSetDeltransData()
8176- SCIPvarHasBinaryImplic()
8177- SCIPgetFixedVars() and SCIPgetNFixedVars()
8178- SCIPgetConss(), SCIPgetNOrigConss() and SCIPgetOrigConss()
8179- SCIPsepaGetNConssFound() and SCIPsepaGetNDomredsFound()
8180- SCIPconstructLP() to force constructing the LP of the current node
8181- SCIPisLPConstructed()
8182
8183### Command line interface
8184
8185- added `write statistics` command to default user dialogs
8186
8187### Changed parameters
8188
8189- modified meaning of parameter `presolving/probing/maxtotaluseless`
8190- heuristics with `freq = 0` and `freqofs > 0` are now called in depth level freqofs instead of being called in the root
8191 node
8192- added some parameters in local branching and RINS heuristic
8193- new parameter values `p`rimal simplex and `d`ual simplex in `lp/initalgorithm` and `lp/resolvealgorithm`
8194
8195### New parameters
8196
8197- `branching/inference/conflictweight`
8198
8199Build system
8200------------
8201
8202### Makefile
8203
8204- included version number in binary file name
8205- tried to make the code Windows compatible
8206
8207Fixed bugs
8208----------
8209
8210- also removed history_length, if `NO_REMOVE_HISTORY` is defined to support older versions of the readline library
8211- hopefully fixed bug with wrong path slash `/` under Windows
8212- fixed bug with aggregating fixed variables
8213
8214- Implications:
8215 - fixed bug in transitive implication addition
8216 - fixed wrong assert with implications that imply a fixed variable
8217 - removed bug in implication addition
8218
8219- Readers:
8220 - fixed bug in ZIMPL model reader with wrong chdir, if .zpl file is in current directory
8221 - fixed bug in LP file reader with signed values without space between sign and value (e.g. `+2x` instead of `+ 2x`)
8222 - fixed various bugs in LP file reader
8223 - fixed bug in LP file reader with explicit zero coefficients
8224
8225- Numerics:
8226 - fixed numerics in probing and linear constraint handler (rentacar was detected to be infeasible in presolving)
8227 - fixed numerics in check method of linear constraint handler
8228 - fixed bug with numerical error in LP resolve after probing or diving
8229
8230- Heuristics:
8231 - fixed bug with calling heuristics in depths smaller than their frequency offset
8232 - fixed bugs in local branching and RINS heuristic
8233
8234Known bugs
8235----------
8236
8237- if one uses column generation and restarts, a solution that contains variables that are only present in the
8238 transformed problem (i.e., variables that were generated by a pricer) is not pulled back into the original space
8239 correctly, since the priced variables have no original counterpart
8240
8241@section RN080 SCIP 0.8.0
8242*************************
8243
8244Features
8245--------
8246
8247- adding variable bounds automatically adds the corresponding implication
8248- changed restart dfs nodeselector to sort leaves by node number instead of node depth to aviod jumping around in the
8249 search tree after a restart was applied and the current dive ended due to infeasibility
8250- new Message Handler plugin
8251- added file reader for LP format
8252- introduced subversion string
8253- replaced all abort() calls by SCIPABORT(); this is defined in def.h to be `assert(FALSE)`
8254- added possibility to disable certain features by using `make USRFLAGS=-DNO_REMOVE_HISTORY`, `make
8255 USRFLAGS=-DNO_SIGACTION`, `make USRFLAGS=-DNO_RAND_R`, or `make USRFLAGS=-DNO_STRTOK_R`
8256- improved preprocessing abort criteria
8257- added zlib support
8258
8259- Conflict Analysis:
8260 - conflict clauses are now collected in a conflict store, redundant clauses are eliminated and only the best `conflict/maxclauses`
8261 clauses are added permanently to the problem; the remaining clauses are only added temporarily, if they can be used for repropagation
8262 - modified the influence of the depth level in conflict analysis
8263 - slightly changed LP resolving loop in conflict analysis
8264 - if CPLEX returns that the LP exceeds the bound and if no additional LP solves are allowed in conflict analysis, we
8265 have to perform one additional simplex iteration to get the dual solution that actually violates the objective limit
8266
8267- Constraints:
8268 - reactivated multiaggregation in cons_linear.c on binary variables again (possible due to bug fix below)
8269 - improved preprocessing of variable bounds constraints
8270 - linear constraint handler now catches events of variables after the problem was completely transformed in order to
8271 avoid the whole bunch of `LOCKSCHANGED` events that are generated at problem transformation stage
8272 - added redundancy detection for pairs of constraints in setppc constraint handler
8273
8274- Presolving and Cliques:
8275 - changed linear constraint presolving s.t. redundant sides are not removed if constraint is an equality
8276 - new event type `SCIP_EVENTTYPE_PRESOLVEROUND`
8277 - modified probing presolver to not add implications that are already included in the implication graph and clique table
8278 - incorporated clique and implication information in knapsack constraint presolving
8279 - removed transitive clique generation, because this produces way too many cliques
8280
8281- Heuristics:
8282 - diving heuristics now apply propagation at each step
8283 - removed `objfeaspump` heuristic, because the functionality can be achieved by using the `feaspump` heuristic
8284 - diving heuristics are now applying propagation after each bound change
8285 - new primal heuristic `octane`
8286 - slightly changed feaspump heuristic, s.t. after finding a new best solution the target integral solution is modified randomly
8287
8288- Separation and Cuts:
8289 - improved debugging for infeasible cuts and propagations, given a primal feasible solution
8290 - improved knapsack cover separation
8291 - improved performance of c-MIR separator
8292 - cut pool is now also separated in root node (to find cuts again that were removed from the LP due to aging)
8293
8294Interface changes
8295-----------------
8296
8297- new event type `SCIP_EVENTTYPE_VARDELETED`
8298- new event `SCIP_EVENTTYPE_IMPLADDED`
8299- new event types `SCIP_EVENTTYPE_GLBCHANGED` and `SCIP_EVENTTYPE_GUBCHANGED`
8300
8301### New and changed callbacks
8302
8303- new callback parameter `validnode` for the `CONFLICTEXEC` method of conflict handlers, which should be passed to
8304 SCIPaddConsNode()
8305
8306### Deleted and changed API methods
8307
8308- additional parameter `validnode` for SCIPaddConsLocal() and SCIPaddConsNode()
8309- SCIPhashtableRemove() can now also be called, if the element does not exist in the table
8310- SCIPhashmapRemove() can now also be called, if the element does not exist in the map
8311- additional parameter `branchdir` for SCIPbranchVar()
8312- replaced method SCIPmessage() by SCIPverbMessage() with additional parameter `file`
8313- put block memory shell and tclique algorithm into separate subdirectories
8314- new parameter `duringlploop` of SCIPincludeHeur(): heuristics can now run during the price-and-cut loop at a node
8315
8316### New API functions
8317
8318- SCIPgetNConflictClausesApplied()
8319- SCIPgetNConflictClausesApplied()
8320- SCIPhashtableExists()
8321- SCIPhashmapExists()
8322- SCIPnodeGetNumber()
8323- SCIPsolveProbingLP() to solve the LP in a probing node (enables mixing of propagation and LP solving for diving heuristics)
8324- SCIProwGetDualfarkas()
8325- SCIPgetCurrentNode()
8326- SCIPinterruptSolve()
8327- SCIPpropagateProbingImplications()
8328- SCIPgetLPI() which makes all methods in scip/lpi.h available to the user
8329- SCIPgetRandomInt() and SCIPgetRandomReal()
8330- SCIPstrtok()
8331- SCIPheurGetNBestSolsFound()
8332
8333- Variables:
8334 - SCIPdelVar()
8335 - SCIPgetVarStrongbranchLPAge()
8336 - SCIPvarIsTransformedOrigvar()
8337 - SCIPvarIsDeleted()
8338
8339- Messages and IO:
8340 - SCIPerrorMessage()
8341 - SCIPwarningMessage()
8342 - SCIPdialogMessage()
8343 - SCIPinfoMessage()
8344 - SCIPsetMessagehdlr()
8345 - SCIPsetDefaultMessagehdlr()
8346 - SCIPgetMessagehdlr()
8347 - new file i/o methods SCIPfopen(), SCIPfclose(), SCIPfprintf(), ... that operate on the data type `SCIPFILE`; these
8348 methods automatically use zlib methods if the zlib is enabled
8349
8350- Cliques:
8351 - SCIPvarGetNCliques()
8352 - SCIPvarGetCliques()
8353 - SCIPvarsHaveCommonClique()
8354 - SCIPvarHasImplic()
8355 - SCIPcliqueGetNVars()
8356 - SCIPcliqueGetVars()
8357 - SCIPcliqueGetValues()
8358 - SCIPcliqueGetId()
8359 - SCIPaddClique()
8360 - SCIPcalcCliquePartition()
8361
8362- Constraint handler:
8363 - SCIPgetDualfarkasLinear() of linear constraint handler
8364 - SCIPgetDualfarkasLogicor() of logicor constraint handler
8365 - SCIPgetDualfarkasSetppc() of setppc constraint handler
8366 - SCIPgetDualsolKnapsack() of knapsack constraint handler
8367 - SCIPgetDualfarkasKnapsack() of knapsack constraint handler
8368 - SCIPgetDualsolVarbound() of varbound constraint handler
8369 - SCIPgetDualfarkasVarbound() of varbound constraint handler
8370 - SCIPconsGetValidDepth()
8371 - SCIPsetConsInitial()
8372 - SCIPsetConsSeparated()
8373 - SCIPsetConsEnforced()
8374 - SCIPsetConsChecked()
8375 - SCIPsetConsPropagated()
8376 - SCIPsetConsLocal()
8377 - SCIPsetConsDynamic()
8378 - SCIPsetConsRemoveable()
8379
8380### Command line interface
8381
8382- added command `write solution` to default dialog
8383- added commands `write problem` and `write transproblem` to default dialog
8384
8385### Changed parameters
8386
8387- additional setting `SCIP_VERBLEVEL_DIALOG` in `display/verblevel` parameter
8388- additional LP pricing setting `partial`
8389- replaced parameter `presolving/restartbdchgs` with parameters `presolving/maxrestarts` and `presolving/restartfac`
8390- replaced parameter `constraints/linear/maxpresolaggrrounds` with `constraints/linear/maxpresolpairrounds`
8391- parameters `constraints/agelimit` and `constraints/obsoleteage` now iterprete the value 0 as a dynamic setting
8392- number of fractional variables included in parameter `separating/maxstallrounds`
8393
8394- Changed default values:
8395 - changed default values of `heuristics/∗/maxdiveavgquot` and `heuristics/∗/maxdiveavgquotnosol` to 0
8396 - changed default values of `constraints/agelimit` and `constraints/obsoleteage` to 0
8397 - changed default values of `heuristics/objpscostdiving/maxsols` and `heuristics/rootsoldiving/maxsols` to -1
8398 - changed default value of `separating/strongcg/maxroundsroot` to 20
8399 - changed default value of `separating/cmir/maxroundsroot` to 10
8400 - changed default value of `constraints/linear/maxaggrnormscale` to 0.0, which means to not apply aggregation
8401 - changed default value of `separating/maxstallrounds` to 5
8402 - changed default value of `presolving/probing/maxfixings` to 50
8403 - changed default parameter values to MIP settings:
8404 + `conflict/useprop` = FALSE
8405 + `conflict/usepseudo` = FALSE
8406 + `display/verblevel` = 4
8407 + `separating/poolfreq` = 0
8408 + `constraints/linear/sepafreq` = 0
8409 + `constraints/and/sepafreq` = 0
8410 + `constraints/conjunction/sepafreq` = 0
8411 + `constraints/knapsack/sepafreq` = 0
8412 + `constraints/knapsack/sepacardfreq` = 0
8413 + `constraints/logicor/sepafreq` = 0
8414 + `constraints/or/sepafreq` = 0
8415 + `constraints/setppc/sepafreq` = 0
8416 + `constraints/varbound/sepafreq` = 0
8417 + `constraints/xor/sepafreq` = 0
8418 + `separating/clique/freq` = 0
8419 + `separating/cmir/freq` = 0
8420 + `separating/gomory/freq` = 0
8421 + `separating/impliedbounds/freq` = 0
8422 + `separating/strongcg/freq` = 0
8423
8424### New parameters
8425
8426- `branching/fullstrong/reevalage`
8427- `conflict/maxclauses`
8428- `conflict/allowlocal`
8429- `constraints/knapsack/disaggregation`
8430- `presolving/probing/maxtotaluseless`
8431- `separating/cmir/maxfails`, `separating/cmir/maxfailsroot` and `separating/cmir/trynegscaling`
8432
8433### Data structures
8434
8435- MAJOR CHANGE: preceeded all data types with `SCIP_`: you may use shell script reptypes_scip.sh to rename the SCIP
8436 data types in your own source code (But use with care! Create a backup copy of your source first!)
8437
8438Build system
8439------------
8440
8441### Makefile
8442
8443- modified the Makefile to accept an additional parameter `VERBOSE={true,false}`
8444- added flags `READLINE=true/false`, `ZLIB=true/false`, `ZIMPL=true/false` to Makefile
8445
8446Fixed bugs
8447----------
8448
8449- fixed minor bugs in debug code of primal.c and sol.c
8450- variables that are being multiaggregated are now automatically removed from all other variables' variable bound and
8451 implication arrays; this fixes bugs with methods, that rely on the fact, that the entries in the variable bound and
8452 implication arrays are active variables only
8453- aggregations are now always performed in a way, such that the variable of more general type is aggregated (with type
8454 generality being cont > implint > int > bin); in this way, a binary variable's representant is always binary (which
8455 was not the case before and resulted in a bug in SCIPgetBinvarRepresentative())
8456- removed bug in presol_probing.c: the vars of the sorted variables array have to be captured
8457- fixed bug in the output of solutions with priced variables
8458- fixed bug in propagation with parameters prop_maxrounds and prop_maxroundsroot
8459- conflict analysis can now handle errors in LP solving calls
8460- removed bug in SCIPvarAddVlb() and SCIPvarAddVub() with fractional vlb/vubcoefs
8461- fixed bug that primal or dual rays might not be available because the wrong solver was used
8462- included message.o in LPI library, s.t. one can link this library indepentent of SCIP
8463- fixed bug that if diving heuristic that changes the objective values finds a solution, the cutoff is reinstalled in
8464 the LP solver (although the objective value has no meaning due to the objective function modification)
8465
8466- Feasibiltiy:
8467 - LP primal feasibility for bounds is now defined as absolute measure (was relative to the bound before); this fixes a bug (see alu8_9.mps),
8468 that an LP with an integral variable fixed to a large value yields an accepted solution with that variable slightly different than the fixed
8469 value; the integrality feasibility condition is measured with absolute differences, which leads to the fixed integer variable being fractional;
8470 this leads to an error if branching is performed on this variable
8471 - fixed bug with redundant self implications that wrongly lead to the detection of infeasibility
8472 - fixed bug with potential infinite loop if a separator is delayed and the LP is infeasible
8473
8474- Asserts:
8475 - removed wrong asserts from lpi_cpx.c
8476 - removed wrong assertion in varAddImplic()
8477
8478- Numerics:
8479 - locally fixed variables are no longer used as branching candidates even if their LP solution value is fractional (due
8480 to numerical reasons, see above)
8481 - fixed numerical bug in pseudo objective propagator with only slightly tightened bounds
8482 - removed bug that an LP might be declared to be solved even if it was marked erroneous due to numerical problems
8483
8484- Constraint Handlers:
8485 - fixed bug in linear constraint handler with variables fixed to infinity
8486 - fixed bug with constraint handlers that can only enforce their constraints by adding cuts, but the maximal number of
8487 cuts to separate is set to 0; now, cuts that are generated in the constraint enforcement are used in any case
8488 - fixed bug in knapsack constraint presolving with tightening coefficients and capacity
8489 - fixed bug with modifiable constraints in linear constraint handler preprocessing
8490 - fixed bug in linear constraint handler that global activities are not updated after global bound changes
8491
8492- Separation and Cuts:
8493 - global bound changes now lead to the removal of redundant implications (such that the asserts in sepa_implbounds.c are now correct)
8494 - due to usage of variable bounds, SCIPcalcMIR() may return LOOSE variables in the cut -> modified sepa_cmir.c, sepa_gomory.c and
8495 sepa_strongcg.c to use SCIPcreateEmptyRow() and SCIPaddVarsToRow() instead of SCIPcreateRow() which only works for COLs
8496 - fixed bug in clique separator that reduced performance
8497 - increased performance of clique separator by allowing only a certain number of zero-weighted fill ins
8498
8499@page RN07 Release notes for SCIP 0.7
8500
8501@section RN079 SCIP 0.7.9
8502*************************
8503
8504Features
8505--------
8506
8507- aging and cleanup now only remove non-basic columns and basic rows, s.t. resolving can be applied with 0 simplex iterations
8508- it is now possible to create subnodes in probing and use backtracking to undo probing changes
8509- bounds of variables are included in the feasibility checks for solutions
8510- support for barrier algorithm
8511- changed implementation of automatic minplungedepth and maxplungedepth calculation in bfs node selector
8512
8513- Presolving:
8514 - new plugin: probing presolver
8515 - probing is now also possible in presolving stage
8516 - it is now possible to interrupt and continue presolving
8517
8518- Separation and Cuts:
8519 - new plugin: clique separator for clique cuts with at least 3 elements
8520 - new plugin: implied bound cuts separator
8521 - included debugging module to check whether cutting planes cut off the optimal solution
8522
8523- Branching:
8524 - changed implementation of reliability value calculation in reliability branching; slightly modified influence of
8525 maximal total number of strong branching LP iterations in reliability branching
8526 - changed implementation of maximal strong branching iterations calculation in reliability branching
8527
8528- Constraints:
8529 - if verblevel is at least `NORMAL`, an automatical check of the best solution is performed in the original problem, and
8530 an error message is displayed, if it violates an original constraint
8531 - due to the new constraint handler `cons_cumulative.{c,h}` SCIP can resource-constraint scheduling problem
8532 - during probing, propagation of bounds is now always performed in linear constraint handler, ignoring the parameter `tightenboundsfreq`
8533 - new implementation of the clique graph construction method in clique separator
8534 - new constraint handler `cons_cumulative.{c,h}`
8535
8536- Heuristics:
8537 - new implementation of the feasibility pump heuristic by Timo Berthold (replaces old implementation); old
8538 implementation is now called `objfeaspump`; parameter names have been changed accordingly
8539 - diving heuristics now compare their number of LP iterations with the number of node LP iterations instead of the total
8540 number (including their own) LP iterations
8541 - modified the automatic objfactor setting of feaspump heuristic to let the objective function have stronger influence
8542
8543Examples and applications
8544-------------------------
8545
8546- added TSP example in `examples/TSP`
8547
8548Interface changes
8549-----------------
8550
8551### New and changed callbacks
8552
8553- new callback methods `INITSOL` and `EXITSOL` for variable pricers, primal heuristics, conflict handlers, relaxators,
8554 separators, propagators, event handlers, node selectors and display columns
8555- callback method `CONFLICTEXEC` of conflict handlers receive additional parameters `dynamic` and `removeable`
8556- constraint handler callback methods `CONSLOCK` and `CONSUNLOCK` are replaced by a single method `CONSLOCK` with the number
8557 of locks being positive or negative
8558
8559### Deleted and changed API methods
8560
8561- calling SCIPaddCut() with `forcecut=TRUE` will add the cut to the LP even if it is redundant
8562- SCIPreadProb() does not free the current problem, this is done in SCIPcreateProb() now, which is usually
8563 called by a problem reader; in this way, a reader can generate `extra information` for the current problem, s.t. the
8564 full problem information can be distributed to different files read by different readers
8565- SCIPgetVarStrongbranch() and SCIPgetVarStrongbranchLast() now have two additional parameters that can be used
8566 to check, whether the returned values are correct dual bounds
8567- SCIPgetBinvarRepresentative() now returns the fixed or multi-aggregated variable instead of returning `NULL` or
8568 aborting with an error message
8569- SCIPdispDecimal() is replaced by SCIPdispInt() and SCIPdispLongint()
8570- additional parameter `maxproprounds` in SCIPpropagateProbing()
8571- changed memory interface (see memory.h), `MEMHDR` is now called `BLKMEM`
8572- source code was moved into subdirectories: replace includes `scip.h` by `scip/scip.h` and
8573 `objscip.h` by `objscip/objscip.h`; This should allow a user to have include files of the same name as the ones
8574 of SCIP, e.g. `tree.h` or `var.h`.
8575- event handlers are now available as C++ wrapper class
8576- new flag `afterrelaxation` for primal heuristics
8577
8578- Solution:
8579 - removed method SCIPsolGetObj(), use SCIPgetSolOrigObj() or SCIPgetSolTransObj() instead
8580 - additional parameter `checkbounds` for SCIPtrySol(), SCIPtrySolFree(), SCIPcheckSol()
8581
8582- Variables:
8583 - SCIPvarLock(), SCIPvarLockDown(), SCIPvarLockUp(), SCIPvarLockBoth(), SCIPvarUnlock(), SCIPvarUnlockDown(),
8584 SCIPvarUnlockUp() and SCIPvarUnlockBoth() are replaced by SCIPaddVarLocks() which returns a `RETCODE`
8585 - SCIPvarGetLbGlobal(), SCIPvarGetUbGlobal(), SCIPvarGetLbLocal() and SCIPvarGetUbLocal() now return the
8586 corresponding values of the transformed problem or current subproblem even for original problem variables
8587 - SCIPvarGetProbvar(), SCIPvarGetProbvarBinary() now return the fixed or multi-aggregated variable instead of
8588 returning `NULL` or aborting with an error message; in SCIPvarGetProbvarBinary(), the fixing of a fixed variable does
8589 not influence the negation status anymore
8590 - SCIPvarGetProbvarBound() returns the multi-aggregated variable instead of aborting with an error message
8591 - SCIPvarGetProbvarSum() does not set *var to `NULL` for fixed variables anymore; it may also return a
8592 multi-aggregated variable instead of aborting with an error message
8593 - SCIPaddVarImplication() now also adds variable lower and upper bounds, if the implied variable is non-binary
8594 - additional parameter `aggregated` in SCIPmultiaggregateVars()
8595
8596- Constraints:
8597 - SCIPvarLockDownCons(), SCIPvarLockUpCons(), SCIPvarUnlockDownCons() and SCIPvarUnlockUpCons() are replaced by
8598 SCIPlockVarCons() and SCIPunlockVarCons() which return a `RETCODE`
8599 - SCIPlockConsVars() and SCIPunlockConsVars() replaced with method SCIPaddConsLocks()
8600 - SCIPconshdlrGetNConss() is replaced by SCIPconshdlrGetNActiveConss() (returning the number of active
8601 constraints); method SCIPconshdlrGetNConss() does now return the total number of existing constraints, active and inactive
8602 - SCIPconshdlrGetStartNConss() is now called SCIPconshdlrGetStartNActiveConss()
8603 - SCIPconshdlrGetMaxNConss() is now called SCIPconshdlrGetMaxNActiveConss()
8604 - SCIPdisableConsNode() is replaced by SCIPdelConsNode()
8605 - SCIPdisableConsLocal() is replaced by SCIPdelConsLocal()
8606 - added new parameter `dynamic` to SCIPcreateCons() and all plugin methods SCIPcreateCons...()
8607
8608### New API functions
8609
8610- SCIPgetObjNorm()
8611- SCIPcreateOrigSol()
8612- SCIPwriteImplicationConflictGraph()
8613- SCIPinProbing()
8614- SCIPgetProbName()
8615- SCIPgetVarNStrongbranchs()
8616- SCIPcolGetNStrongbranchs()
8617- SCIPfindSimpleRational()
8618- SCIPselectSimpleValue()
8619
8620- Variables:
8621 - SCIPvarGetLbOriginal()
8622 - SCIPvarGetUbOriginal()
8623 - SCIPvarGetImplIds()
8624 - SCIPvarGetOrigvarSum()
8625
8626- Constraints:
8627 - SCIPenableCons()
8628 - SCIPdisableCons()
8629 - SCIPenableConsSeparation()
8630 - SCIPdisableConsSeparation()
8631 - SCIPconsIsSeparationEnabled()
8632
8633- Averages:
8634 - SCIPgetAvgPseudocost()
8635 - SCIPgetAvgPseudocostCurrentRun()
8636 - SCIPgetAvgPseudocostCount()
8637 - SCIPgetAvgPseudocostCountCurrentRun()
8638 - SCIPgetAvgInferences()
8639 - SCIPgetAvgInferencesCurrentRun()
8640 - SCIPgetAvgCutoffs()
8641 - SCIPgetAvgCutoffsCurrentRun()
8642
8643- LPs:
8644 - SCIPisLPSolBasic() to check, whether the current LP solution is basic (i.e. due to a simplex algorithm or barrier with crossover)
8645 - SCIPgetNPrimalLPs()
8646 - SCIPgetNPrimalLPIterations()
8647 - SCIPgetNDualLPs()
8648 - SCIPgetNDualLPIterations()
8649 - SCIPgetNBarrierLPs()
8650 - SCIPgetNBarrierLPIterations()
8651 - SCIPgetNPrimalResolveLPs()
8652 - SCIPgetNPrimalResolveLPIterations()
8653 - SCIPgetNDualResolveLPs()
8654 - SCIPgetNDualResolveLPIterations()
8655
8656- Delayed:
8657 - SCIPsepaIsDelayed()
8658 - SCIPsepaWasDelayed()
8659 - SCIPpropIsDelayed()
8660 - SCIPpropWasDelayed()
8661 - SCIPpresolIsDelayed()
8662 - SCIPpresolWasDelayed()
8663 - SCIPconshdlrIsSeparationDelayed()
8664 - SCIPconshdlrIsPropagationDelayed()
8665 - SCIPconshdlrIsPresolvingDelayed()
8666 - SCIPconshdlrWasSeparationDelayed()
8667 - SCIPconshdlrWasPropagationDelayed()
8668 - SCIPconshdlrWasPresolvingDelayed()
8669
8670### Command line interface
8671
8672- command line history in interactive shell now only stores useful commands
8673
8674### Interfaces to external software
8675
8676- removed storing of dual norms in LPI state of CPLEX interface (too memory consuming)
8677
8678### Changed parameters
8679
8680- default frequency offset of fracdiving heuristic changed to 3
8681- default frequency offset of (new) feaspump heuristic changed to 0
8682- default frequency offset of objfeaspump heuristic changed to 8
8683- changed default priority of primal heuristics
8684- renamed parameter `limits/sol` to `limits/solutions`
8685- changed default check priority of knapsack constraint handler to -600000
8686- changed default priority of Gomory cut separator to -1000 (will now be called after constraint handlers!)
8687- changed default priority of strong CG cut separator to -2000
8688- changed default priority of cmir cut separator to -3000
8689- changed default of parameter `lp/pricing` to `s`teepest edge pricing
8690- default parameter `branching/relpscost/minreliable` changed to 1.0
8691- default parameter `branching/relpscost/maxlookahead` changed to 8
8692- default parameter `branching/relpscost/sbiterofs` changed to 100000
8693- default parameter `heuristics/coefdiving/maxlpiterquot` changed to 0.05
8694- default parameter `heuristics/fracdiving/maxlpiterquot` changed to 0.05
8695- default parameter `heuristics/guideddiving/maxlpiterquot` changed to 0.05
8696- default parameter `heuristics/linesearchdiving/maxlpiterquot` changed to 0.05
8697- default parameter `heuristics/pscostdiving/maxlpiterquot` changed to 0.05
8698- default parameter `heuristics/feaspump/freq` changed to 20
8699- default parameter `heuristics/objfeaspump/freq` changed to 20
8700- default parameter `heuristics/objpscostdiving/freq` changed to 20
8701- default parameter `heuristics/rootsoldiving/freq` changed to 20
8702- default parameter `separating/clique/maxtreenodes` changed to -1
8703
8704### New parameters
8705
8706- new parameter delay for presolvers
8707- new parameter delaypresol for constraint handlers
8708- `branching/scorefunc`
8709- `constraints/.../delaypresol`
8710- `constraints/.../delayprop`
8711- `constraints/.../delaysepa`
8712- `conflict/dynamic`
8713- `conflict/removeable`
8714- `heuristics/coefdiving/maxlpiterofs`
8715- `heuristics/feaspump/maxlpiterofs`
8716- `heuristics/feaspump/maxsols`
8717- `heuristics/fracdiving/maxlpiterofs`
8718- `heuristics/guideddiving/maxlpiterofs`
8719- `heuristics/linesearchdiving/maxlpiterofs`
8720- `heuristics/objfeaspump/maxlpiterofs`
8721- `heuristics/objfeaspump/maxsols`
8722- `heuristics/objpscostdiving/maxlpiterofs`
8723- `heuristics/objpscostdiving/maxsols`
8724- `heuristics/pscostdiving/maxlpiterofs`
8725- `heuristics/rootsoldiving/maxlpiterofs`
8726- `heuristics/rootsoldiving/maxsols`
8727- `heuristics/fixandinfer/proprounds` and `heuristics/fixandinfer/minfixings`
8728- `lp/cleanupcolsroot` and `lp/cleanuprowsroot` to distinguish cleanup settings between root node and other nodes
8729- `lp/checkstability` to disable stability check of LP solver's result code
8730- `lp/initalgorithm` and `lp/resolvealgorithm` for switching between simplex and barrier algorithm
8731- `lp/pricing` to set the pricing strategy used in the LP solver
8732- `numerics/barrierconvtol` to set the convergence tolerance in the barrier algorithm
8733- `presolving/.../delay`
8734- `propagating/.../delay`
8735- `reading/cnfreader/dynamicconss`
8736- `reading/mpsreader/dynamicconss`
8737- `separating/.../delay`
8738
8739### Data structures
8740
8741- new possible result `SCIP_DELAYED` for `EXEC` method of separators, presolvers and propagators and `SEPA`, `PROP` and
8742 `PRESOL` methods of constraint handlers
8743
8744Fixed bugs
8745----------
8746
8747- fixed bug in MPS file reader
8748- removed bug with applying reduced cost strengthening before pricing in all necessary variables
8749- negated variables must also be reset in SCIPvarInitSolve()
8750- fixed documentation of `CONSLOCK`-method (missing parameter `scip` in SCIPaddVarLocks())
8751- included missing `objrelax.h` in includes of objscip.h
8752- fixed bug that after a resolve and further preprocessing, existing primal solutions may get corrupted due to
8753 aggregations or fixings that are possible due to the primal bound (given by the best solution)
8754- fixed bug with primal bound becoming wrong, if in a prior run the optimal solution was found and the cutoff bound was
8755 thereby reduced due to further domain propagation w.r.t. the objective function
8756- fixed bug in SCIPisObjIntegral()
8757- fixed bug in SCIPprintError() with `file == NULL`
8758- heuristic's display character is now only shown the first time, the new solution was found
8759- fixed bug that SCIPreadProb() doesn't discard the transformed problem
8760- fixed bug with wrong euclidean norm calculation of row, if multiple coefficients for the same variable are added and
8761 the sorting of the row was delayed with SCIProwDelaySort()
8762- fixed bug with adding implications: wrong insertion position, if only the lower bound change was present but not the
8763 upper bound change
8764- fixed bug in SCIPvarAddImplics() with wrong variable used in varAdjustBd()
8765- fixed bug in method reduced() of tclique_branch.c with sorting nodes in V
8766
8767- LP:
8768 - removed bug with objective norm calculation and column variables not in the LP (pricing)
8769 - LP error on forced LP resolve (due to 0 unfixed integers) now leads to an error (instead of accepting the pseudo
8770 solution as feasible)
8771 - fixed bug in CPLEX LP interface with dual norms
8772
8773- Presolving:
8774 - fixed bug that presolving time is not counted to solving time, if presolving is called explicitly with SCIPpresolve()
8775 - fixed bug where presolving fixings are counted even if the variable was already fixed
8776 - removed bug with dual presolver, that declared a problem to be unbounded or infeasible, if it could fix a variable to
8777 infinity even if its objective value is zero
8778 - fixed bug in knapsack constraint handler that fixed variables are sometimes not removed in presolving
8779
8780- Numerics:
8781 - fixed bug with unresolved numerical troubles in LP that don't render the LP useless at the current node
8782 - fixed numerical bugs in rounding heuristic and rootsoldiving heuristic
8783
8784- Separator:
8785 - fixed bugs in separation store with single coefficient cuts that are converted into bound changes
8786 - at least one cut per separation round is added to the LP to avoid cycling, even if the cut is redundant
8787 - fixed bug in SCIProwCalcIntegralScalar() with rows consisting of only continuous variables (appeared in gomory cut
8788 separator on miplib/dcmulti.mps)
8789 - fixed bug in linear constraint handler's knapsack relaxation separator
8790 - fixed bugs in intobj separator
8791 - fixed bug in cmir separator with empty rows
8792 - fixed bug in implied bound cut separator: only implications between binary variables were generated before
8793
8794- Constraint Handlers:
8795 - removed bug in knapsack constraint handler with merging multiple items if more than two items of the same variable
8796 appear in the constraint
8797 - removed bug in knapsack constraint handler with merging negated variables of equal weight at the end of the variables' array
8798 - fixed bug in linear constraint handler with eventdatas, if the original constraint has no variables
8799 - fixed bug that `CONSLOCK` method of constraint handlers that don't need constraints is not called
8800 - fixeg bug in setppc constraint handler with pairs of aggregated variables in the same constraint
8801 - fixed bug with globally deleting constraints, that have attached rows which are therefore not released in exitsol methods
8802
8803- Conflict analysis:
8804 - removed conflict analysis of infeasible diving LP if pricing is activated
8805 - made conflict analysis available in presolving stage (for probing conflicts)
8806
8807@section RN078 SCIP 0.7.8
8808*************************
8809
8810Features
8811--------
8812
8813- changed SCIProwCalcIntegralScalar() to a slightly different algorithm
8814- improved knapsack relaxation in linear constraint handler separator to scale the constraint in order to get integral
8815 coefficients instead of just rounding down all coefficients
8816- improved presolving of linear constraint handler: aggregation of two constraints with equal coefficient vector into
8817 single constraint
8818- improved presolving of knapsack constraint handler: aggregation of equal or negated variables in same constraint
8819
8820- Plugins:
8821 + priority of separators, propagators and presolvers decide whether the plugin is called before the corresponding
8822 constraint handler methods or after: plugins with nonnegative priorities are called before, plugins with negative
8823 priorities are called after the constraint handlers
8824 + new plugin class for relaxators (external relaxations, that can be used in parallel with LP relaxations)
8825 + if more than one result code applies to a plugin's execution, it should return the one that is higher in the call's
8826 documentation list
8827
8828Interface changes
8829-----------------
8830
8831- even in optimized mode, the simple functions that are implemented as defines in the include files exist in the
8832 library, s.t. one can include the include files without `NDEBUG` and use the optimized library
8833
8834### New and changed callbacks
8835
8836- new branching rule plugin methods `INITSOL` and `EXITSOL`
8837
8838### Deleted and changed API methods
8839
8840- removed SCIPisFeasible(); use !SCIPisFeasNegative() instead
8841- SCIPisIntegral(), SCIPisFracIntegral(), SCIPfloor(), SCIPceil() and SCIPfrac() don't use the feasibility
8842 tolerance anymore (default: 1e-06); instead, they are using epsilon (default: 1e-09); instead, for handling
8843 integrality of a variable `in feasibility tolerances`, new methods SCIPisFeasIntegral(), SCIPisFeasFracIntegral(),
8844 SCIPfeasFloor(), SCIPfeasCeil() and SCIPfeasFrac() should be used
8845- in LPI, the semantics of SCIPlpiHasPrimalRay() and SCIPlpiHasDualRay() changed: methods return TRUE, if a ray exists
8846 and the solver can return it; new methods SCIPlpiExistsPrimalRay() and SCIPlpiExistsDualRay() check whether a ray
8847 exists without checking, if the solver knows and can return the ray
8848
8849### New API functions
8850
8851- SCIPvarIsInLP()
8852- SCIPgetLPColumnObjval() and SCIPgetLPLooseObjval()
8853- SCIPcalcIntegralScalar() with arbitrary array of Real values
8854- SCIPaddCoefKnapsack() in knapsack constraint handler
8855- SCIPisScalingIntegral() to check, whether the scaling of a value would lead to an integral value, measured
8856 against epsilon which is also scaled by the same scalar
8857- SCIPgetRealarrayMinIdx(), SCIPgetRealarrayMaxIdx(), SCIPgetIntarrayMinIdx(), SCIPgetIntarrayMaxIdx(),
8858 SCIPgetBoolarrayMinIdx(), SCIPgetBoolarrayMaxIdx(), SCIPgetPtrarrayMinIdx() and SCIPgetPtrarrayMaxIdx()
8859- SCIPbsortPtrInt() and SCIPbsortPtrIntInt()
8860- SCIPvarWasFixedAtIndex()
8861- SCIPaddConflictBd()
8862- SCIPprintMemoryDiagnostic()
8863- SCIPfindObj...() and SCIPgetObj...() in C++ wrapper interface to get the corresponding plugin object
8864
8865### Changed parameters
8866
8867- slightly changed the meaning of parameter `presolving/abortfac` a value of 0 now means to abort presolving only after
8868 no more change has been found
8869
8870Fixed bugs
8871----------
8872
8873- assigning a value to a fixed variable in a solution with SCIPsetSolVal() does not return an error anymore, if the
8874 value is equal to the fixed value of the variable
8875- removed bug in SCIPisScalingIntegral()
8876- removed bugs with calling SCIPtightenVarLb(), SCIPtightenVarUb(), SCIPinferVarLbCons(), SCIPinferVarUbCons(),
8877 SCIPinferVarLbProp() and SCIPinferVarUbProp() in `PROBLEM` stage
8878
8879- (Re)solving:
8880 - solving loop is now immediately aborted, if a node on the active path is marked to be cut off
8881 - removed bug in resolving an interrupted problem, after the last solved node was cut off
8882 - removed bug with infinite solving loop if LP solving is turned off
8883 - removed bug with aborted solving in root node (e.g. due to time limit) that is tagged to be restarted
8884
8885- Branching:
8886 - fixed bug in all-fullstrong branching with getting strong branching information for columns not in current LP
8887 - implemented missing case in solve.c with branching rules that add constraints
8888
8889- Numerics:
8890 - changed numerics for integrality check of coefficients (fixed bug with accumulated errors in rows s.t. the row's
8891 activity is no longer integral although the row is marked being integer)
8892 - slightly changed numerics in linear constraint handler presolving to fix a bug with coefficients detected to be scaled
8893 to an integral value, that are not integral after scaling due to a large scalar that increased the integrality gap to
8894 a value larger than epsilon
8895
8896- Constraint handlers:
8897 - fixed bugs in consdataSwitchWatchedVars() of `or` and `and` constraint handlers
8898 - fixed wrong assertion in xor constraint handler with switching both watched variables to unwatched
8899 - fixed bugs in constraint handlers (and, logicor, or, setppc, xor) with calling conflict analysis during presolving
8900 - removed bug in knapsack constraint handler that appears if a variable is fixed to zero in knapsack presolving, which
8901 triggers a variable of the same knapsack to be fixed to one due to aggregation
8902
8903- Presolving:
8904 - removed bug in knapsack presolver
8905 - fixed bug in presolving with wrong number of newly fixed/aggregated/... variables/bounds/... after a restart
8906
8907@section RN077 SCIP 0.7.7
8908*************************
8909
8910Features
8911--------
8912
8913- infeasible LPs in diving now produce conflict clauses (if LP conflict analysis is enabled)
8914- conflict analysis was slightly modified
8915- slightly changed aging strategy of logic or constraint handler
8916
8917Interface changes
8918-----------------
8919
8920### Deleted and changed API methods
8921
8922- method SCIPgetGap() and SCIPgetTransGap() now return infinity, if primal and dual bound have opposite sign (this
8923 removes the oddness with the gap increasing while the dual bound approaches zero)
8924
8925### New API functions
8926
8927- added methods SCIPgetVarsLogicor() and SCIPgetNVarsLogicor() in logic or constraint handler
8928
8929### Changed parameters
8930
8931- `lp/colagelimit` and `lp/rowagelimit` may now be set to -1 to disable deletion of columns/rows due to aging
8932
8933Build system
8934------------
8935
8936### Makefile
8937
8938- the file names in the archive file are now preceeded with a directory `scip-<version>/`
8939- the compiler is now also represented in the LP solver library names (e.g. you have to rename the softlink
8940 `libcplex.linux.x86.a` to `libcplex.linux.x86.gnu.a`)
8941
8942Fixed bugs
8943----------
8944
8945- removed bug in conflict analysis that appears if the conflict is only active at the current depth level
8946- missing SCIPlpiIsPrimalFeasible() and SCIPlpiIsDualFeasible() implemented in lpi_spx.cpp and lpi_spx121.cpp
8947- removed preprocessing of linear constraint pairs with modifiable constraints
8948
8949- Asserts:
8950 - removed wrong assert `assert(eventfilter->len == 0 || eventfilter->eventmask != 0x00000000)` from event.c
8951 - removed wrong assert in conflict analysis (appeared on analyzing diving LP conflicts with both bounds of a non-binary variable changed)
8952
8953@section RN076 SCIP 0.7.6
8954*************************
8955
8956Features
8957--------
8958
8959- creation of reconvergence clauses in conflict analysis
8960- first node of each plunging is not treated as plunging node w.r.t. calling primal heuristics
8961- improved performance of logic or constraint handler due to better watched variables handling
8962
8963Interface changes
8964-----------------
8965
8966### Deleted and changed API methods
8967
8968- changed SCIPcatchVarEvent() and SCIPdropVarEvent()
8969- SCIPstage() is now called SCIPgetStage()
8970- SCIPprintStatus() is now called SCIPprintStage()
8971
8972### New API functions
8973
8974- SCIPgetActivityLinear() in linear constraint handler
8975- SCIPgetFeasibilityLinear() in linear constraint handler
8976- SCIPchgVarBranchDirection()
8977- SCIPvarGetBranchDirection()
8978- SCIPgetStatus() returns the solution status
8979- SCIPprintStatus() outputs the solution status (beware, that the old SCIPprintStatus() method is now called SCIPprintStage())
8980
8981### Changed parameters
8982
8983- changed default frequency offset of pscostdiving `heuristics/pscostdiving/freqofs` to 2 and frequency offset of fracdiving
8984 `heuristics/feaspump/freqofs` to 0 in order to not call pscostdiving in root node, where nearly all pseudo costs are uninitialized.
8985
8986### New parameters
8987
8988- new parameter `separating/efficacynorm` to choose between Euclidean, maximum, sum and discrete norm in efficacy
8989 calculation
8990
8991### Data structures
8992
8993- new possible result code `SCIP_DELAYED` for primal heuristics
8994
8995Fixed bugs
8996----------
8997
8998- removed bugs in CLP Solver interface
8999- SCIP returned `gap limit reached` even if the problem was solved to optimality, if the optimal solution was found at a
9000 node with lower bound equal to the global lower bound
9001- after conversion of the focus node into a junction (e.g. in case of numerical troubles while solving the node's LP), the child
9002 nodes got the wrong LP fork attached (the common LP fork of the old and new focus node instead of the old focus node's LP fork)
9003
9004- Variables:
9005 - bug reconvergence clauses in conflict analysis if bounds on non-binary variables were the reason for the fixing of the
9006 uip to create a reconvergence clause for
9007 - wrong sub calls in SCIPvarGet...CurrentRun() for aggregated variables
9008 - variables' conflict set counter was not reset when the problem was resolved again
9009
9010Known bugs
9011----------
9012
9013- unbounded models lead to an error
9014- air04 and air05 return wrong optimal value (1 too large): possibly due to strong branching or setppc propagation?
9015
9016@section RN075 SCIP 0.7.5
9017*************************
9018
9019Miscellaneous
9020-------------
9021
9022- started change log*/