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AMPL > >Products > >Solvers > >Gecode Options for AMPL

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:

valvalue propagation or consistency (naive)
bndbounds propagation or consistency
domdomain propagation or consistency
defthe 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:

noneno restarts
constantrestart with constant sequence
linearrestart with linear sequence
lubyrestart with Luby sequence
geometricrestart 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:

minsmallest value (default)
medgreatest value not greater than the median
maxlargest value
rndrandom value
split_minvalues not greater than mean of smallest and largest value
split_maxvalues greater than mean of smallest and largest value
range_minvalues from smallest range, if domain has several ranges; otherwise, values not greater than mean of smallest and largest value
range_maxvalues from largest range, if domain has several ranges; otherwise, values greater than mean of smallest and largest value
values_minall values starting from smallest
values_maxall values starting from largest
var_branching

Variable branching. Possible values:

nonefirst unassigned
rndrandom
degree_minsmallest degree
degree_maxlargest degree
afc_minsmallest accumulated failure count (AFC)
afc_maxlargest accumulated failure count (AFC)
activity_minlowest activity
activity_maxhighest activity
min_minsmallest minimum value
min_maxlargest minimum value
max_minsmallest maximum value
max_maxlargest maximum value
size_minsmallest domain size (default)
size_maxlargest domain size
degree_size_minsmallest domain size divided by degree
degree_size_maxlargest domain size divided by degree
afc_size_minsmallest domain size divided by AFC
afc_size_maxlargest domain size divided by AFC
activity_size_minsmallest activity by domain size
activity_size_maxlargest activity by domain size
regret_min_minsmallest minimum-regret
regret_min_maxlargest minimum-regret
regret_max_minsmallest maximum-regret
regret_max_maxlargest 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