[Scip] Tentative branching not working

[Tobias Achterberg]

nikolaj at crt.umontreal.ca wrote:
> Indeed, just setting 'initial' to TRUE is sufficient. Actually, using
> constraints/linear/sepafreq = 1 gives me a strange (to me) result :
> while I'm not using the knapsack constraint (I'm not using
> SCIPincludeDefaultPlugins(scip_) nor SCIPincludeConshdlrKnapsack(scip_)),
> for some graphs, scip is aborting with this message :
> 
>  src/scip/cons_knapsack.c:2120: SCIPseparateRelaxedKnapsack: Assertion `0
> <= SCIPvarGetProbindex(var) && SCIPvarGetProbindex(var) < nbinvars'
> failed.
> 
> Is this normal ? If I don't use the setting constraints/linear/sepafreq =
> 1, no problem arises.

It is normal that knapsack cover cuts are separated: this is also done by the linear constraint handler. It
relaxes the linear constraints to knapsack constraints and then calls the corresponding method of the knapsack
constraint handler.

But it is not normal that you get the assertion. This is something that you need to investigate further. I
suggest that you are doing a joint debugging session together with Kati Wolter (wolter at zib.de).


Tobias