[SCIP] Questions on detecting unbounded

[Yankai Cao]

Dear Benjamin, 


Thanks so much for your reply.  Is there any parameter I can set to help SCIP detect if the problem is unbound. For example, for my model, if SCIP find an upper bound <= ub (e.g. -1e10), I want SCIP to stop and declare the problem is unbound. Otherwise, it will takes SCIP much much more time to continue. Thanks.


Regards,
Yankai


> On Feb 17, 2017, at 7:19 AM, Benjamin Müller <benjamin.mueller at zib.de> wrote:
> 
> Dear Yankai,
> 
> you can use
> 
> 	set/limits/objective
> 
> in order to set an objective limit. SCIP will then only look for solutions that have a better value than the given objective limit. You can think of it as an artificial upper bound for your (minimization) problem.
> 
> As far as I can see it, there is no parameter to set an initial dual bound in SCIP. There is SCIPupdateLocalDualbound in the API that could be called during the SCIP_STAGE_PROBLEM stage.
> 
> Regards,
> Benjamin
> 
> 
> On 02/17/2017 07:24 AM, Yankai Cao wrote:
>> Hi, All,
>> 
>> I am new to SCIP.  I want to know how to set a parameter  ub (e.g. -1e10) so that if SCIP find the upper bound is smaller than ub SCIP can stop and declare that the problem is unbounded?
>> 
>> Also,  how to provide known upper/lower bounds before b&b, which might help speed the solution time of SCIP?
>> 
>> Thanks very much!
>> 
>> 
>> Regards,
>> Yankai
>> 
>> 
>> _______________________________________________
>> Scip mailing list
>> Scip at zib.de
>> http://listserv.zib.de/mailman/listinfo/scip
>> 
> 
> -- 
> ______________________________
> Benjamin Müller
> Zuse Institute Berlin
> Takustr. 7, 14195 Berlin
> benjamin.mueller at zib.de
> +49 30 841 85-195