[SCIP] Setting relative gap in FiberSCIP and ParaSCIP

[Sergey Smirnov]

Hi Yuji,

Thank you for checking my instance.

We also tried setting CheckGapInLC=TRUE but it did not help either.

Best regards,
Sergey


> On 11 Sep 2022, at 17:42, Yuji Shinano <shinano at zib.de> wrote:
> 
> Hi Sergey,
> 
> Thanks for the instance and configuration. I checked it.
> Sorry, in the current implementation of FiberSCIP and ParaSCIP, controlling it only with the SCIP parameter looks difficult when it takes time to solve
> (if it can be solved in the racing stage, the "NoPreprocessingInLC = TRUE" might work).
> And it looks like the setting SCIP parameters for that is not good for FiberSCIP and ParaSCIP in a sense how it work is not clear.
> I will add the feature rather UG side in the future. I think it can not control vividly, but when LC recognized that gap is reached,
> then LC interrupts all computations from the UG side.
> 
> Best regards,
> Yuji
> 
> --------------
> Hi Yuji,
> 
> Here are the instance and configuration files attached.
> 
> Thank you in advance,
> Best regards,
> Sergey
> 
> 
> > On 10 Sep 2022, at 08:55, Yuji Shinano <shinano at zib.de> wrote:
> >
> > Hi Sergey,
> >
> > Can you send me the instance and parameters (UG and SCIP)? I will check it.
> >
> > Best regards,
> > Yuji
> >
> > On 10.09.22 6:50, Sergey Smirnov wrote:
> >> Hi Yuji,
> >>
> >> Thank you for the suggestion. I tried to set NoPreprocessingInLC = TRUE in ug.set but both fscip and parascip still solved till zero gap.
> >>
> >> Best regards,
> >> Sergey
> >>
> >>> On 9 Sep 2022, at 21:20, Yuji Shinano <shinano at zib.de> wrote:
> >>>
> >>> Hi,
> >>>
> >>> This is one of the frequently asked questions. FiberSCIP/ParaSCIP solves the presolved instance in the Solvers.
> >>> Therefore, the value is applied to solve the presolved instance. If you would like to control the gap more precisely,
> >>> one way would be to set
> >>>  NoPreprocessingInLC = TRUE
> >>> In the UG parameter file.
> >>> However, this means that layered presolving does not work and may decrease its performance.
> >>> Please try to run with the above parameter.
> >>>
> >>> Best,
> >>> Yuji
> >>>
> 
> 
> On 09.09.22 19:45, Sergey Smirnov wrote:
>> Hello, SCIP community,
>> 
>> I have problems setting relative gap in parallel version of SCIP 8.0.1.
>> 
>> When I set limits/gap = .5e-01 in scip.set and run scip like scip -f problem.cip -s scip.set  scip stops after reaching the gap specified. However, fscip and parascip seem to ignore this parameter. For example, I run fscip the following way and it solves until optimality:
>> fscip ug.set problem.cip -s scip.set
>> 
>> What is the correct way to set relative gap in fscip/parascip?
>> 
>> Thank you in advance,
>> Best regards,
>> Sergey
>> 
>> 
>> _______________________________________________
>> Scip mailing list
>> Scip at zib.de
>> https://listserv.zib.de/mailman/listinfo/scip
> 
> 
> -- 
> --------------------------------------------------
> Yuji Shinano
> Zuse Institute Berlin
> Takustrasse 7, 14195 Berlin-Dahlem, Germany
> Phone:+49 30 84185-477, Fax:+49 30 84185-269
> 
> _______________________________________________
> Scip mailing list
> Scip at zib.de
> https://listserv.zib.de/mailman/listinfo/scip

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listserv.zib.de/pipermail/scip/attachments/20220912/009c4804/attachment.html>