[Scip] finding cutting planes is scip2.0.1 and scip2.1.0

Stefan Heinz heinz at zib.de
Wed Jun 6 08:39:49 MEST 2012


Hi James,

to ge an idea what happens, could ypu please rerun the example and call

SCIP_CALL( SCIPprintStatistics(scip, NULL) );
http://scip.zib.de/doc/html/scip_8h.html#a6e7eb26b996d4466493a504a0924a35d

before you kill SCIP. These statistics might give us a hint.

Stefan


On 06/05/12 09:43, James Cussens wrote:
> I have a constraint handler which includes some code for finding
> cutting planes for a machine learning problem (Bayesian net learning).
> With SCIP 2.0.1 this works well. The routine for finding the cutting
> planes (a sub-MIP which uses a depth-first search, no linear
> relaxation finds (usually several) good cutting planes. Moving to SCIP
> 2.1.0 the story is very different. On even very easy problems vast
> numbers of useless cutting planes are found.
>
> The two attached files tell the story. With SCIP 2.0.1 13 cutting
> planes are enough to solve the problem. With SCIP 2.1.0 I had to
> terminate the process after very many (mostly bad) cutting planes had
> been generated.
>
> My code is the same in both cases, except to account for the extra
> constraint handler argument in SCIP 2.1.0. The attached files were
> produced just after a fresh install of the two SCIPs just to be sure.
>
> Perhaps there is a simple explanation. Some crucial change to a
> default value, perhaps.
>
> Any ideas? I'm happy to send out my source(s) if that would help anyone.
>
>
>
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