[SCIP] Difficulty in restarting B&B; SCIPreleaseVar Assertion failed with my constraint handler

[Dev Anand]

Hi,

Sorry for the typo. Instead " the branch restarts I get the error message
just after the solver calls ", it will be
" the *branch and bound* restarts I get the error message just after the
solver calls "

Regards,
Devanand


On Fri, Aug 20, 2021 at 10:17 AM Dev Anand <dev.ismdhanbad at gmail.com> wrote:

> Dear Scipers,
>
> I am new to SCIP. I am trying to implement my own brancher in scip. My
> brancher requires storing some relevant information at each branching node.
> The FAQ provided in SCIP documentation guided me to create a
> constraint_handler for this. As mentioned I took the help of constraint
> handler of the coloring problem
> (examples/Coloring/src/cons_storeGraph.c)).  To get the data stored in a
> constraint, I have written external methods to my constraint handler.
> The brancher works fine and my constraint handler helps in storing and
> fetching the relevant data at each branching node. But, when the branch
> restarts I get the error message just after the solver calls
> SCIPsetExitsolPlugins.
> The message I get is:
> SCIPreleaseVar: Assertion `(*var)->scip == scip' failed.
>
> When I debugged, I found that after executing SCIP_DECL_CONSEXITSOL and
> SCIP_DECL_CONSDELETE in my constraint handle without any error, it stuck on
> SCIPsepaExitsol in deinitialization method of *clique* *separator.*
> When I further looked into it, the tcliquegraphFree in sepa_clique.c,
> calls the method SCIPreleaseVar. And surprisingly the first variable
> itself, when I check (*var)->scip = 0x0, failed with  Assertion
> `(*var)->scip == scip' failed.
>
> Currently, I am only adding one constraint to my constraint handler when
> the B&B process is about to begin (in the method SCIP_DECL_CONSINITSOL).
> So, I am not using SCIP_DECL_CONSACTIVE and SCIP_DECL_CONSDEACTIVE methods.
> I use my external methods to fetch and store the consdata information.
>
> I would like to know how my constraint handle is linked with the tclique
> separator. I am finding difficulty in resolving this issue. Please help me
> to resolve it.
>
> Regards,
> Devanand
>
>
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