[AMPL 15302] User defined Gomory Cuts in AMPL

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[AMPL 15302] User defined Gomory Cuts in AMPL

Tasnim Faiz
Hello All,

Is it possible to write user defined Gomory Cuts in AMPL (while suppressing those from the CPLEX solver)? Is there any example available?

Thank you.

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RE: [AMPL 15306] User defined Gomory Cuts in AMPL

Robert Fourer-2
You can turn off CPLEX's Gomory cut generation by adding fraccuts=-1 to AMPL's cplex_options string (see http://ampl.com/products/solvers/solvers-we-sell/cplex/options/), or you can turn off all cut generation in CPLEX with cutpass=-1.

However it is not possible to generate cuts in AMPL and send them to CPLEX, while CPLEX is running.  Also the information needed to generate new Gomory cuts is not provided by CPLEX to AMPL.  To do your own cut generation within the CPLEX algorithm you would need to use one of the solver-specific interfaces for CPLEX, which provide access to callbacks from a running CPLEX process; these interfaces are in IBM's CPLEX distribution.

Bob Fourer
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From: [hidden email] [mailto:[hidden email]] On Behalf Of TFaiz
Sent: Tuesday, December 5, 2017 12:46 PM
To: AMPL Modeling Language
Subject: [AMPL 15302] User defined Gomory Cuts in AMPL

Is it possible to write user defined Gomory Cuts in AMPL (while suppressing those from the CPLEX solver)? Is there any example available?


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