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