[Scip] Lower bound in branch and price method

[Marco Lübbecke]

First short: you do not generate "all" columns, that is, your pricing
problem is buggy. Check whether you calculate reduced costs correctly,
check whether your pricing problem formulation is correct, verify with toy
examples that you can (and do) solve by hand for comparison.

Bests,
Marco



2013/8/6 Mahdi Noorizadegan (DIMAP) <phd09mn at mail.wbs.ac.uk>

> Dear SCIP,
>
> I am trying to solve a variant of VRP in SCIP within branch and price
> algorithms.
> The problem is that after few iterations without any dual bound and
> infinite gap, it generates a lower bound which is higher than the optimal
> solution of the instance I solve.
> I was wondering if you could help me to understand how SCIP generates the
> dual bound and why while it is still in early stages it generates very high
> lower bound?
>
> Thanks
> Mahdi
>
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-- 
Prof. Dr. Marco Lübbecke
RWTH Aachen University
Chair of Operations Research
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Germany

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