[Scip] Fractional Solution

[Benjamin Müller]

Dear Bahereh,

so your problem contains only the reformulated (binary) psi variables? 
Your problem is that you do not want to accept all integer psi solutions 
because they might correspond to a fractional solution of the original 
problem? If that is the case, do you decline such a solution in 
CONSCHECK? How do you branch in the CONSENFOLP after you registered that 
the current solution belongs to a fractional one in the original space? 
Do you set the result pointer to SCIP_BRANCHED?


Best,

Benny


On 07/27/2015 03:36 AM, Bahareh Eghtesadi wrote:
> Dear all,
>
> I am implementing a b&p algorithm. In my problem, I have a set of 
> binary variables (beside  the decomposition variables) in my master 
> problem, call them psi,  for which I have a branching rule. In my 
> branching rule, the options for constructor is:
> ObjBranchrule( scip, name, "branchs on Original vars", 50000 , -1 , 1.0)
>
> I also want to check the integrality of the original variables(call 
> x). For that, I have a conshdlr with following options:
>
> ObjConshdlr(scip, name, "....",-10000 , 50000 , 10000, -1,  -1 , 1 , 0 
> , FALSE , FALSE , FALSE , FALSE , SCIP_PROPTIMING_BEFORELP)
>
> In this conshdlr, in the CONSENFOLP method, I find the values of the 
> original variables and if they are not integer, I call SCIPcreateChild.
>
> However, in the optimal solution, all the psi variables are binary, 
> but the original variables are continuous. The objective function 
> value is also less than the optimal obj. value(I already know it).
> I have tried to track down the b&b tree, and it seems whenever all the 
> binary variables(psi) are binary, it takes it as the optimal solution 
> eventhough there are some fractional x.
> I also changed the priority of the conshdlr to be less than the 
> branching rule's. Then, the same solution is caught with less number 
> of nodes(quicker).
>
> I am not sure how to check what happens after the psi s are binary, 
> and why it doesnt go to the CONSENFOLP method after that. Is there a 
> reason for happening this?
> I attached the output file with statistics and the branching statistics.
>
> Thanks in advance.
>
>
>
>
> _______________________________________________
> 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

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listserv.zib.de/pipermail/scip/attachments/20150728/14fd709a/attachment.html>