[Scip] How to terminate SCIP earlier?

[lixiangyong at 163.com]

Dear Dr. Ambros,

I want to know the advantage of  calling SCIPsetObjIntegral() if at the beginning I know any feasible solution should have an integer objective value?  Can it speed up the solving process?

Thanks,

Xiangyong Li

 
From: Ambros Gleixner
Date: 2014-09-24 08:21
To: scip; lixiangyong at 163.com
Subject: Re: [Scip] How to terminate SCIP earlier?
Dear Xiangyong,
 
 
Am 24.09.2014 02:08, schrieb lixiangyong at 163.com:
> Dear Dr. Gerald,
>
> Thanks,  I have used SCIPinterruptSolve() to terminate my solving
> process since I know the current incumbent is the optimal solution.
>
> BTW, can you tell me the advantage of  calling SCIPsetObjIntegral() if I
> know any feasible solution should have an integer objective value?  Can
> it speed up the solving process?
 
Yes.  If (in minimization) the primal bound is x and the lower bound is 
greater than  x - 1, the solution process can be stopped already.
 
Best regards,
Ambros
 
 
>
>
> Thanks,
>
>
> Xiangyong
>
>     *From:* Gerald Gamrath <mailto:gamrath at zib.de>
>     *Date:* 2014-09-23 17:16
>     *To:* lixiangyong at 163.com <mailto:lixiangyong at 163.com>; scip
>     <mailto:scip at zib.de>
>     *Subject:* Re: [Scip] How to terminate SCIP earlier?
>     Dear Xiangyong Li,
>
>     if you know that every feasible solution will have an integer
>     objective value and therefore want to stop the solving process when
>     the dualbound is larger than primalbound - 1, you can just inform
>     SCIP that this is the case by calling SCIPsetObjIntegral().
>
>     Otherwise, you can call SCIPinterruptSolve() to stop the solving
>     process, but SCIP will then print that it was interrupted, not that
>     it was solved to optimality.
>
>     Best,
>     Gerald
>
>     Am 23.09.2014 um 10:02 schrieb lixiangyong at 163.com:
>>     Dear all,
>>
>>     I am using SCIP to implement my branch and price algorithm.
>>     Now I want to terminate the SCIP earlier since I can judge the
>>     problem has been optimally solved when some condition is satisfied.
>>     Suppose UB and LB be the objective value of best incumbent and the
>>     best remaining node in the branch and bound tree.
>>     For my instances considered, SCIP has optimally solved one
>>     instance if UB-LB < 1.
>>
>>     Can you tell me how to set the earlier termination condition in SCIP?
>>
>>     Thanks,
>>
>>
>>     Xiangyong Li
>>
>>
>>
>>
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>
>
>
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-- 
____________________________________________________________
Ambros M. Gleixner
Zuse Institute Berlin - Matheon - Berlin Mathematical School
http://www.zib.de/gleixner
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