[Scip] Postprocessing

[Timo Berthold]

Hi Mathieu.

Bound strenghtening techniques are automatically applied in the
propagation callbacks of certain constraint handlers (linear, knapsack,
quadratic,...) which interacts with the price-and-cut loop of SCIP,
basically in the following way: propagate->solve LP->price->cut->(if new
vars or cuts found, start again). Also, reduced cost strengthening (which
actually is a form of propagation/bound strenghtening) is applied only
during the separation round. The reason is that this one first needs the
LP to be solved to optimality.
If you just use SCIP as a blackbox solver, I hope this answered your
question.

If you like to set up your own domain propagation routine (node
pre-processing), you will have to implement a propagation plugin (see How
to add propagators in the Doxygen-Docs) or the propagation callback of a
constraint handler (see How to add constraint handlers). If you need a
solved LP for your method (hend it rather is a post-processing), you
probably better implement a separator (How to..., see also
src/scip/sepa_redcost.c) or the separation callbac of a constraint
handler.


Best regards,
Timo

 > Hello everybody,
>
> My apologies if this is obvious, but how can I do some postprocessing work
> (bound strenghtening) after the price-and-cut loop has run?
>
>
> Regards,
>
> Mathieu
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