[Scip] Fwd: Separation for equality knapsack constraints

[Benjamin Müller]

Dear Christina,

yes you are right, there is no equality knapsack constraint handler in 
SCIP anymore. As far as I know the cons_eqknapsack was never really 
included to SCIP. I guess there is a better way to handle such equality 
constraints in another plug-ins.

I think adding your constraint as linear constraint to SCIP is 
absolutely fine. In general SCIP upgrades constraints into constraints 
of other types if SCIP detects the necessary structure for the targeting 
constraint type. You can find possible upgrades for linear constraints 
by starting SCIP in the terminal with

bin/scip -c "set cons linear upgrade"

and of course in the documentation.


Best regards,

Benny


On 03/25/2015 04:14 PM, Cristina Núñez del Toro wrote:
>
> Hello to all,
>
> I'm trying to separate a set of constraints that are equality knapsack 
> constraints. I was looking around the scip documentation and I found 
> that there is a constraint handler for eqknapsack constraints 
> (cons_eqknapsack.h), so I thought it could be easier if I include the 
> equality knapsack constraints using "SCIPcreateConsEqknapsack" instead 
> of "SCIPcreateConsLinear" and then separate it automatically without 
> detecting by hand the violated cover inequality.
>
> However, when I include the constraint handler 
> (SCIPincludeConshdlrEqknapsack), I got a compilation error since it is 
> not declared in the scope. I tried to include the header 
> "scip/cons_eqknapsack.h" but there is not such file or directory.
>
> I realized that I was looking the documentation for version 2.0.2 and 
> I'm using 3.1.0. However, for this last version, I only found the 
> constraint handler for knapsack constraints of the form Ax <= b , but 
> not for Ax = b. I guess there is not such constraint handler anymore? 
> If so, is there another way so I can take advantage of your already 
> defined plugins/callbacks in order to apply separation to the equality 
> constraints?
>
> Thanks in advance.
>
>
> -- 
> Cristina Nuñez
>
>
>
> -- 
> ---
> Cristina Nuñez
>
>
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-- 
______________________________
Benjamin Müller
Zuse Institute Berlin
Takustr. 7, 14195 Berlin
benjamin.mueller at zib.de
+49 30 841 85-195

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