[Scip] Threads and incremental solutions

[Gerald Gamrath]

Hi Raphael,

> 1) Is it possible to use more than one core?
you can do this via the ug framework which comes with the SCIP
optimization Suite 3.0 / 3.0.1, but this won't work together with the
python interface.
> 2) In a very long running optimization where a feasible solution is
> found quickly, can scip output its best feasible solution so far as it
> goes along?
You already see the SCIP output and how the primal bound changes, but
you also want to see the solution values of all variables whenever SCIP
finds a new solution? There is no method within SCIP to do that, but you
can easily implement it within SCIP as an event handler. Please have a
look at the Eventhdlr example, in particular src/event_bestsol.c, in
which you would need to print the solution via SCIPprintSol() instead of
printing a message via SCIPinfoMessage(). Also, you could stop the
solving process, print the current best solution and restart the
solving, but I'm not sure whether this is possible via the python code.

Do you need to build the problem, start the optimization and evaluate
the results from within python? If you just want to model a problem and
run it, you might want to try out ZIMPL, the modeling language of the
SCIP Optimization Suite.

Best,
Gerald