[Scip] cutting plane questions

Thorsten Koch koch at zib.de
Sun Jul 28 21:02:01 MEST 2013


Hi Felix,

could you provide us an LP file of the instance and a
short discription what you are modelling?

The number of variables has no clear connection to the
effectiveness of B&C.

Best regards,
Thorsten

Am 28.07.2013 20:42, schrieb Felix Breuer:
> Hello everyone!
> 
> I am trying to solve a hard mixed-integer program to optimality. However,
> branch and bound seems to be largely ineffective at finding an optimal
> solution, simply because the search space is way too large. (There are 512
> binary variables in my program, and I know for theoretical reasons that all
> 2^512 ways of fixing these variables lead to a feasible solution.) I'd like
> to experiment with using cutting planes more aggressively to solve the
> problem, and I have a couple of questions:
> 
> 0) The "cuts" given by SCIP on the command line when solving the problem -
> do these number give the number of cuts currently in the system, or do they
> give the total number of cuts that have been added in the entire run?
> 
> 1) I tried adjusting the many parameters the SCIP offers for controlling
> separators. However, I have been unable to make SCIP use more than about
> 150 cuts. How can make SCIP use even more cutting planes?
> 
> 2) In particular, is there a way to configure SCIP not to use
> branch-and-bound at all but only cutting planes to solve the problem? I
> know that conventional wisdom says this is hopelessly inefficient. But I'd
> like to investigate how this approach fares on my problems.
> 
> Thank you!
> 
> Felix
> 
> 
> 
> 
> 
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-- 
The important thing is not to stop questioning.
Curiosity has its own reason for existing.          -- Albert Einstein
______________________________________________________________________
Dr. Thorsten Koch / Konrad-Zuse-Zentrum für Informationstechnik Berlin
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koch at zib.de     /                     Phone +49-30-84185-213, Fax -269
_______________/  DFG Research Center "Matheon"  http://www.matheon.de

Kooperativer Bibliotheksverbund Berlin Brandenburg  http://www.kobv.de
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