[SCIP] Adding separating cuts at root node only

[Naga Venkata Chaitanya Gudapati - nagavenkata.gudapati@studio.unibo.it]

Thanks a lot!

 my version of subtour detection takes way too much time and I was hoping to save the time. Thanks for the link. I was just going by the comments of the code.

________________________________________
From: Scip <scip-bounces at zib.de> on behalf of Gerald Gamrath <gamrath at zib.de>
Sent: Wednesday, July 15, 2020 7:53 PM
To: scip at zib.de
Subject: Re: [SCIP] Adding separating cuts at root node only

Hi Naga,

no, it cannot be disabled, because it is checking the feasibility of
solutions and without it, the algorithm is not correct anymore, see
https://www.scipopt.org/doc-7.0.1/html/CONS.php#CONSCHECK

Best,

Gerald

Am 15.07.20 um 19:32 schrieb Naga Venkata Chaitanya Gudapati -
nagavenkata.gudapati at studio.unibo.it:
> Thanks a lot Filipe and Ambros,
>
> SCIP_DECL_CONSCHECK(scip_check) is being called again and again after after the branching starts. Is there a way to disable it once branching starts?
>
> Thanks a lot!
> Naga
>
> ________________________________________
> From: Scip <scip-bounces at zib.de> on behalf of Felipe Serrano <fserranom5 at gmail.com>
> Sent: Wednesday, July 15, 2020 6:49 PM
> To: SCIP mailing list
> Subject: Re: [SCIP] Adding separating cuts at root node only
>
> Hi
>
> In this particular example, notice also that the function findSubtour gets called in CONSCHECK as well!
>
> Best,
> Felipe
>
> On Wed, Jul 15, 2020 at 5:23 PM Ambros Gleixner <gleixner at zib.de<mailto:gleixner at zib.de>> wrote:
> Dear Naga,
>
> This could happen when a sub-SCIP heuristic is called in the tree.  You
> could check this by printing SCIPgetProbName(), since sub-SCIP
> heuristics typically append their name to the problem name of the
> original SCIP.
>
> Best,
> Ambros
>
>
> Am 15.07.20 um 16:51 schrieb Naga Venkata Chaitanya Gudapati -
> nagavenkata.gudapati at studio.unibo.it<mailto:nagavenkata.gudapati at studio.unibo.it>:
>> Hello SCIP community,
>>
>> I have created a constraint handler using the following piece of c++ code
>>
>> ObjConshdlr(scip, "subour", "subtour 3_constraints",
>>            1000000, -2000000, -2000000, 0, -1, 1, 0,
>>            FALSE, FALSE, TRUE, SCIP_PROPTIMING_BEFORELP, SCIP_PRESOLTIMING_FAST)
>>
>> I used the TSP example as foundation and followed the documentation here, https://www.scipopt.org/doc/html/classscip_1_1ObjConshdlr.php
>>
>> I am keeping sepafreq at 0 so that the cuts are only added at the root node. But I noticed that some of the functions of the constraint handler like findSubtour are still getting called after the branching starts. Is there something else I have to do?
>>
>> Thanks for the help,
>> Naga
>> _______________________________________________
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>> Scip at zib.de<mailto:Scip at zib.de>
>> https://listserv.zib.de/mailman/listinfo/scip
>>
> --
> Ambros Gleixner, Research Group Mathematical Optimization Methods at
> Zuse Institute Berlin, http://www.zib.de/gleixner
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