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The solver ilogcp connects IBM ILOG CPLEX CP Optimizer and CPLEX to AMPL via the Concert API. It fully supports AMPL extensions for logic and constraint programming and can handle wide range of problems including linear, mixed-integer, quadratic and constraint programming problems.

Normally the ilogcp solver is invoked by AMPL's solve command, which gives the invocation

ilogcp stub -AMPL

in which is an AMPL generic output file (possibly written by ampl -obstub or ampl -ogstub). After solving the problem, the solver writes a stub.sol file for use by ampl's solve and solution commands. When you run ampl, this all happens automatically if you give the AMPL commands

option solver ilogcp;

You can control the solver by setting the environment variable ilogcp_options appropriately (either by using ampl's option command, or by using the shell's set and export commands before you invoke ampl). You can put one or more (white-space separated) option assignments in $ilogcp_options. The option version doesn't take a value:

Phrase Meaning
version Report version details before solving the problem.

Others are name-value pairs separated by '=', as in


which limits CP Optimizer search time to 600 seconds. Options such as logverbosity, that take enumerated list of values, accept both numeric and string values, so


is equivalent to


In particular, switches that take values 0 or 1 also accept values off or on.

The following command prints the full list of options with descriptions:

ilogcp -=

See IBM ILOG CPLEX CP Optimizer Options for AMPL for the full list of options.

solve_result_num values

Here is a table of solve_result_num values that ilogcp can return to an AMPL session, along with the text that appears in the associated solve_message.

Value Message
0 optimal solution
100 feasible solution
200 infeasible problem
201 infeasible or unbounded problem
300 unbounded problem
400 limit
403 solution limit
500 error
600 interrupted

If you invoke ilogcp stub -AMPL or ilogcp stub, you can also supply additional command-line arguments of the form name=value. Such arguments override specifications in $ilogcp_options. Example:

ampl -obfoo foo.model
nohup ilogcp -s foo timing=1 2>>times&

to solve a problem whose solution will take a while; after it finishes,

ampl foo.model -
solution foo.sol;
display ... /* things involving the computed solution */;

(Here, - denotes standard input, and ampl reads the solution... and display... lines.)