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IBM ILOG CPLEX CP Optimizer Options for AMPL

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

ampl: option ilogcp_options 'optimalitytolerance=1e-6 searchtype=restart';

Options

alldiffinferencelevel

Inference level for alldiff constraints. Possible values:

  • default
  • low
  • basic
  • medium
  • extended

The default value is default, which allows the inference strength of all alldiff constraints to be controlled via defaultinferencelevel.

branchlimit
Limit on the number of branches made before terminating a search. Default = no limit.
choicepointlimit
Limit on the number of choice points created before terminating a search. Default = no limit.
constraintaggregation
0 or 1 (default 1): Whether to aggregate basic constraints.
countsolutions
0 or 1 (default 0): Whether to count the number of solutions and return it in the .nsol problem suffix.
debugexpr
0 or 1 (default 0): Whether to print debugging information for expression trees.
defaultinferencelevel

Inference level for constraints that have inference level set to default. Possible values:

  • low
  • basic
  • medium
  • extended

The default value is basic.

distributeinferencelevel

Inference level for aggregated numberof (IloDistribute) constraints. Possible values:

  • default
  • low
  • basic
  • medium
  • extended

The default value is default, which allows the inference strength of all aggregated numberof constraints to be controlled via defaultinferencelevel.

dynamicprobing

Use probing during search. Possible values:

  • auto
  • off
  • on

The default value is auto.

dynamicprobingstrength
Effort dedicated to dynamic probing as a factor of the total search effort. Default = 0.03.
faillimit
Limit on the number of failures allowed before terminating a search. Default = no limit.
logperiod
Specifies how often the information in the search log is displayed.
logverbosity

Verbosity of the search log. Possible values:

  • quiet
  • terse
  • normal
  • verbose

The default value is quiet.

mipdisplay

Frequency of displaying branch-and-bound information (for optimizing integer variables):

0 (default) – never
1 – each integer feasible solution
2 – every mipinterval nodes
3 – every mipinterval nodes plus information on LP relaxations (as controlled by display)
4 – same as 2, plus LP relaxation info.
5 – same as 2, plus LP subproblem info.
mipinterval
Frequency of node logging for mipdisplay 2 or 3. Default = 0.
multiobj
0 or 1 (default 0): Whether to use multi-objective optimization. If set to 1 multi-objective optimization is performed using lexicographic method with the first objective treated as the most important, then the second objective and so on.
multipointnumberofsearchpoints
Number of solutions for the multi-point search algorithm. Default = 30.
objno

Objective to optimize:

0 – none
1 – first (default, if available)
2 – second (if available), etc.
optimalitytolerance
Absolute tolerance on the objective value. Default = 0.
optimizer

Specifies which optimizer to use. Possible values:

autoCP Optimizer if the problem has nonlinear objective/constraints or logical constraints, CPLEX otherwise
cpCP Optimizer
cplexCPLEX Optimizer

The default value is auto.

outlev
Synonym for logverbosity.
propagationlog

Level of propagation trace reporting. Possible values:

  • quiet
  • terse
  • normal
  • verbose

The default value is quiet.

randomseed
Seed for the random number generator. Default = 0.
relativeoptimalitytolerance
Relative tolerance on the objective value. Default = 1e-4.
restartfaillimit
Number of failures allowed before restarting search. Default = 100.
restartgrowthfactor
Increase of the number of allowed failures before restarting search. Default = 1.05.
searchtype

Type of search used for solving a problem. Possible values:

  • auto
  • depthfirst
  • restart
  • multipoint

The default value is auto.

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.
temporalrelaxation
0 or 1 (default 1): Whether to use temporal relaxation.
timelimit
Limit on the CPU time spent solving before terminating a search. Default = no limit.
timemode

Specifies how the time is measured in CP Optimizer. Possible values:

  • cputime
  • elapsedtime

The default value is cputime.

timing
0 or 1 (default 0): Whether to display timings for the run.
usenumberof
0 or 1 (default 1): Whether to aggregate numberof expressions by use of IloDistribute constraints.
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
workers
Number of workers to run in parallel to solve a problem. In addition to numeric values this option accepts the value auto since CP Optimizer version 12.3. Default = auto.