[SCIP] Meaning of assertion assert(lp->validsollp == stat->lpcount)

[Marc Pfetsch]

Hi Alex,

can you please check whether your propagation method terminates the 
probing mode correctly (SCIPendProbing)? It also might be that you call 
functions that disturb the LP status somehow.

If the problem is not immediate from your code, you could run your code 
in a debugger and add a watchpoint on lp->validsollp and stat->lpcount 
and see which function changes it. This might help to track the problem 
down.

Best

Marc




On 19/10/2023 13:37, Alexander Helber wrote:
> Dear SCIP community,
> 
> I am working on a Benders Decomposition where I also implement a 
> propagator that tries to fix some variables by solving probing LPs. For 
> many instances this works without problem but sometimes, the assertion 
> `assert(lp->validsollp == stat->lpcount);` of the function 
> SCIPlpRemoveRedundantRows in line 15956 of `lp.c` is triggered. This 
> happens after my propagator was called, when SCIP resumes solving the 
> current node LP, but not every time. It does not seem to indicate any 
> big problems, as I seem to get correct solutions when I ignore the 
> assertion. If I do not use my propagator, the error does not seem to occur.
> 
> In any case, I wonder if someone has an idea what is going wrong and if 
> it may have negative consequences.
> 
> All the best,
> Alex
> 
> -- 
> Alexander Helber
> Research and Teaching Assistant
> 
> Chair of Operations Research
> RWTH Aachen University
> Kackertstrasse 7
> 52072 Aachen
> Germany
> Web: or.rwth-aachen.de
> Mail:helber at or.rwth-aachen.de
> 
> 
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