Gecode Options for AMPL

To set these options, assign a string specifying their values to the AMPL option gecode_options. For example:

ampl: option gecode_options 'version nodelimit=30000 val_branching=min';

Options

a_d
Adaptive recomputation distance.
c_d
Commit recomputation distance.
countsolutions
0 or 1 (default 0): Whether to count the number of solutions and return it in the .nsol problem suffix.
decay
Decay factor for AFC and activity branchings. Default = 1.
faillimit
Fail limit.
icl

Consistency level for integer propagators. Possible values:

val value propagation or consistency (naive)
bnd bounds propagation or consistency
dom domain propagation or consistency
def the default consistency for a constraint
nodelimit
Node limit.
outfreq
Output frequency in seconds. The value should be a positive number.
outlev
0 or 1 (default 0): Whether to print solution log.
restart

Restart sequence type. Possible values:

none no restarts
constant restart with constant sequence
linear restart with linear sequence
luby restart with Luby sequence
geometric restart with geometric sequence
restart_base
Base for geometric restart sequence. Default = 1.5.
restart_scale
Scale factor for restart sequence. Default = 250.
solutionlimit
Limit on the number of feasible solutions found before terminating a search. Leaving the solution limit unspecified will make the optimizer search for an optimal solution if there is an objective function or for a feasible solution otherwise.
solutionstub
Stub for solution files. If solutionstub is specified, found solutions are written to files (solutionstub & '1' & '.sol') ... (solutionstub & Current.nsol & '.sol'), where Current.nsol holds the number of returned solutions. That is, file names are obtained by appending 1, 2, ... Current.nsol to solutionstub.
threads

The number of parallel threads to use. Assume that your computer has m processing units and that the value for threads is n.

  • If n = 0, then m threads are used (as many as available processing units).
  • If n >= 1, then n threads are used (absolute number of threads to be used).
  • If n <= −1, then m + n threads are used (absolute number of processing units not to be used). For example, when n = −6 and m = 8, then 2 threads are used.
  • If 0 < n < 1, then n * m threads are used (relative number of processing units to be used). For example, when n = 0.5 and m = 8, then 4 threads are used.
  • If −1 < n < 0, then (1 + n) * m threads are used (relative number of processing units not to be used). For example, when n = −0.25 and m = 8, then 6 threads are used.

All values are rounded and at least one thread is used.

timelimit
Time limit in seconds.
timing
0 or 1 (default 0): Whether to display timings for the run.
val_branching

Value branching. Possible values:

min smallest value (default)
med greatest value not greater than the median
max largest value
rnd random value
split_min values not greater than mean of smallest and largest value
split_max values greater than mean of smallest and largest value
range_min values from smallest range, if domain has several ranges; otherwise, values not greater than mean of smallest and largest value
range_max values from largest range, if domain has several ranges; otherwise, values greater than mean of smallest and largest value
values_min all values starting from smallest
values_max all values starting from largest
var_branching

Variable branching. Possible values:

none first unassigned
rnd random
degree_min smallest degree
degree_max largest degree
afc_min smallest accumulated failure count (AFC)
afc_max largest accumulated failure count (AFC)
activity_min lowest activity
activity_max highest activity
min_min smallest minimum value
min_max largest minimum value
max_min smallest maximum value
max_max largest maximum value
size_min smallest domain size (default)
size_max largest domain size
degree_size_min smallest domain size divided by degree
degree_size_max largest domain size divided by degree
afc_size_min smallest domain size divided by AFC
afc_size_max largest domain size divided by AFC
activity_size_min smallest activity by domain size
activity_size_max largest activity by domain size
regret_min_min smallest minimum-regret
regret_min_max largest minimum-regret
regret_max_min smallest maximum-regret
regret_max_max largest maximum-regret
version
Single-word phrase: report version details before solving the problem.
wantsol

In a stand-alone invocation (no -AMPL on the command line), what solution information to write. Sum of

1 - write .sol file
2 - primal variables to stdout
4 - dual variables to stdout
8 - suppress solution message