[SCIP] After stopping pricing and doing restart, model is becoming unbounded during presolve?

[Ambros Gleixner]

Hi Christian,

Strange indeed.  Have you tried to turn off presolving?  Does it still 
happen?  Have you tried to successively activate individual presolvers 
to see when it starts failing?

Best,
Ambros


Am 04.01.21 um 17:10 schrieb Franzen, Christian:
> Hi Scip Team.
> 
> 
> Thanks to the help of Gregor, I managed to make SCIP stop pricing after 
> some iterations and doing a restart on the reduced master without 
> pricing. Unfortunately, I am facing some really strang behaviour. 
> Sometime it happens, that my model (for that I already have found a 
> feasible solution), is reported to be unbound. I wrote the corresponding 
> LP files before and after presolving to disk and I see that some 
> variable bounds vanished, which seems to be the reason for the 
> unboundness. Furthermore, some of the objective coefficients changed 
> their sign. Any ideas how or why that is happening during presolving?
> 
> 
> Regards
> 
> Christian
> 
> 
> P.S.: I attach the SCIP log for one of these runs.
> 
> 
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