[SCIP] Using debugsol with branching rules

[Ambros Gleixner]

Dear Matheus,

Your approach with the debug solution is definitely right.  The fact 
that branching inequalities are reported as violated constraints, 
however, could mean that you are not using the right flags for your 
branching constraints.  Can it be that the "check" flag is set to TRUE? 
  This should not be the case, since they do not belong to the 
definition of feasibilty.

Best,
Ambros


Am 01.07.22 um 02:29 schrieb Matheus Ota:
> Dear Scip Community,
> 
> I'm currently trying to debug my C++ program which incorrectly outputs a 
> non-optimal solution. I have a minimization problem and I have a 
> solution with value 673. My program when executed on my computer claims 
> that a solution with value 674 is optimal. However, if I execute this 
> program on another computer, it correctly outputs a solution with value 
> 673. There are also instances where my computer is correct, but the 
> other computer is not.
> 
> In order to debug this problem I've compiled SCIP with -DDEBUGSOL=on and 
> I'm using the parameter "misc/debugsol" to pass the solution with value 
> 673. One thing to mention is that I have custom branching rules which 
> were implemented via constraint handlers. When I execute the program 
> with the debug solution it is printing a lot of violated constraints in 
> the terminal, however, the violated constraints all seem to correspond 
> to the branching inequalities. Is there a way to suppress the errors 
> specifically for these inequalities?
> 
> Also, I would be thankful for any help here (as I'm getting out of ideas 
> of where the bug is)! I've checked my branching constraints and indeed, 
> if a solution is cut-off in one branch, then it is present in the other 
> branch. So the branching constraints are just partitioning the set of 
> feasible solutions (as expected).
> 
> Thanks for your time,
> Matheus
> 
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