[Scip] Heuristics - Shift and Propagate

[Stephen J Maher]

Hi Gregor,

I have been using the updated file that you sent to me. It worked well.

Unfortunately I am having another problem with the shift and propagate 
heuristic. I have disabled it by setting the frequency parameter to -1, 
however I am getting the error

src/scip/heur_shiftandpropagate.c:1464: heurExecShiftandpropagate: 
Assertion `SCIPisFeasEQ(scip, lb, ub)' failed

Is there a way for me to avoid this error?

Thanks for your help,

Steve



Gregor Hendel wrote:
> Hi Steve,
>
> I have changed the file heur_shiftandpropagate.c, s.t. it should work 
> now. In the attachment, you'll find the file. Just replace
> the old version in <scip-base-dir>/src/scip by the new one. I'm not 
> able to test it on column generation codes, so
> please inform me if this bugfix has fixed your problem sufficiently.
>
>> HI Gregor,
>>
>> I have run my code using the debugger gdb and it seems that the 
>> problem with this heuristic occurs when the rens heuristic is called. 
>> The problem still exists when I disable both, the rens and 
>> shift-and-propagate, heuristics. If I disable all of the heuristics 
>> the problem doesn't occur.
>>
>> I am adding variables dynamically. I have a variable pricer that adds 
>> variables representing network flows. I am also adding constraints of 
>> the problem through a version of benders decomposition. At each 
>> iteration I am removing all variables from the master problem and 
>> reinitialising using the optimal variables from the previous iteration.
>>
>> The problem is written as a MIP with the network flow variables being 
>> binary and there is a set of continuous variables as well.
>>
>> Thanks a lot for your help.
> Thank you for helping us developing a more stable SCIP version.
>
> Best, gregor
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