[Scip] non valid solution using SCIP in the pricing

[Stefan Heinz]

Hi Hélène,

can you please upgrade to SCIP 3.0.1 and check if the error still 
arises. The upgrade should be easy since the interface did not change. 
The 3.0.1 contains basically only bug fixes compared to 3.0.0

Thanks Stefan

On 02/14/2013 08:58 AM, Hélène Toussaint wrote:
> Dear all,
>
> I use SCIP 3.0.0 to run a column generation program. I have sometimes 
> (very rarely) an issue when solving my sub problem with SCIP during 
> the pricing: the solution doesn't respect all the constraints. I 
> enclose a LP ("subPb.lp") for which SCIP gives the solution y11=1; 
> y18=1; y25=1 (all other variables are 0). The constraint cR_0 is 
> violated by this solution (since it involves " cR_0 : 18 <= 15"). This 
> problem only occurs when I use a subSCIP: if I use SCIPreadProb 
> directly on the LP enclosed then SCIP gives the exact result (there 
> exists several solutions whose objective = 1) .
>
> I had a look to the transformed problem (enclosed as "transSubPb.lp"). 
> In this transformed problem, the bounds force variables t_y7, t_y17 
> and t_26 to be 1. But this violate the cR_2 constraint, so this 
> problem is infeasible (while the original problem is feasible...).
>
> I have encountered a very similar problem few months ago (solutions 
> violating constraints on instances for which the objective function is 
> parallel to a ranged row) and it was solved by the enclosed patch 
> (given by Stefan). But this time the violated constraint appears in 
> the transformed problem.
>
> Could you please help me with this issue?
>
> Best regards,
>
> Hélène
>
>
>
>
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