AMPL: A Modeling Language for Mathematical Programming

## Gecode Directives for AMPL

To set these directives, assign a string specifying their values to the AMPL option gecode_options. For example:
```     ampl: option gecode_options 'version nodelimit=30000 val_branching=min';
```

```a_d

c_d
Commit recomputation distance.

faillimit
Fail limit.

memorylimit
Memory limit.

nodelimit
Node limit.

outfreq
Output log frequency in seconds.  The value should be a positive integer.

outlev
0 or 1 (default 0):  Whether to print solution log.

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
* 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.

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_min - 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)
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
size_degree_min - smallest domain size divided by degree
size_degree_max - largest domain size divided by degree
size_afc_min    - smallest domain size divided by AFC
size_afc_max    - largest domain size divided by AFC
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
```