[SCIP] "adding constraints during pricing" revisited

[Benjamin Müller]

Dear Myroslav,

after looking into SCIPpriceLoop of scip/solve.c, I think that it should 
work fine to add your constraints after generating variables in your 
pricer plug-in. After the executing method of each pricer is called, 
SCIP is calling SCIPinitConssLP, which makes sure that all initial 
constraints have been added to the LP. So, probably, you want to mark 
your (linear) constraints to be initial and in case you want to add 
dynamically other variables to them, you also need to set the modifiable 
flag to TRUE.

Another solution might be to add a constraint handler that keeps track 
of the generated variables and then adds the required constraints during 
enforcement.

Best,
Benny


On 09/04/2018 07:35 PM, myroslav wrote:
>
> Dear SCIP community,
>
>
> I am implementing a branch and price algorithm for a problem. When I 
> price my variables I also need to add constraints where they appear. I 
> came across this issue
>
> http://listserv.zib.de/pipermail/scip/2012-April/000935.html
>
> but  I did not find a solution. Does scip support adding constraints 
> in a pricer and what would be the proper way of doing this, which 
> flags of SCIPaddConsLinear should I watch for?
>
>
> Thanks,
>
> Myroslav
>
>
>
>
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> Scip at zib.de
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