[Scip] help : for expressing constraint

[Abdelkader Ouali]

Dear Ambros,
Thank's for replying,
Yes, I don't have a choice, I tried with the indicator constraint, but I don't get it right.Now, I'm trying to use big-M notation or other MIP reformulation Kind regards
--A. Ouali

> Date: Fri, 18 Jul 2014 09:16:04 +0200
> From: gleixner at zib.de
> To: scip at zib.de
> Subject: Re: [Scip] help : for expressing constraint
> 
> Dear Abdelkader Ouali,
> 
> SCIP does not provide a constraint handler for this type of equivalence. 
>   If you do not want to model it via simple linear big-M constraints, 
> then you could use two indicator constraints, see
> 
>     http://scip.zib.de/doc/html/cons__indicator_8h.php
> 
> For the implication Y == 0 -> Ct Xt != 0 you can use SCIPgetNegatedVar() 
> on Y, see
> 
>  
> http://scip.zib.de/doc/html/scip_8h.php#a94ec8a6bca8e6e621751b4257bf0d4c1
> 
> I assume that because Xt are binary, you can express Ct Xt != 0 as a 
> linear equality or inequality constraint.
> 
> (Because the indicator constraint handler only enforces inequalities, 
> maybe you need to indicator constraints to model Y==1 -> Ct Xt == 0 as 
> Ct Xt <= 0 and Ct Xt >= 0, if one of them is not globally valid.  In 
> this case it may be more efficient to write an your own big-M formulation.)
> 
> Best regards,
> ambros
> 
> 
> 
> Am 16.07.2014 16:52, schrieb Abdelkader Ouali:
> > Dear SCIP users,
> >
> > I have a constraint as follow :
> >
> > Y=1 <-> Ct Xt = 0
> > where :
> > Y : is binary variable
> > Xt : is binary set of binary variables
> > Ct : is constant (coefficient) associated to each Xt
> > I had some problems to formulate it in SCIP, since there is equivalence
> > between to linear constraints
> >
> > Can you give some help to implement it ?
> >
> > ---
> > A. Ouali
> >
> >
> > _______________________________________________
> > Scip mailing list
> > Scip at zib.de
> > http://listserv.zib.de/mailman/listinfo/scip
> >
> 
> -- 
> ____________________________________________________________
> Ambros M. Gleixner
> Zuse Institute Berlin - Matheon - Berlin Mathematical School
> http://www.zib.de/gleixner
> _______________________________________________
> Scip mailing list
> Scip at zib.de
> http://listserv.zib.de/mailman/listinfo/scip
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listserv.zib.de/pipermail/scip/attachments/20140718/22bca5af/attachment.html>