[Scip] Deactivating constraints

Tobias Achterberg achterberg at zib.de
Tue Aug 17 16:15:32 MEST 2010


No, this should not be done via a presolver. The original model should be the one that you want to solve. Thus, you need to modify 
the original model before calling SCIPsolve().

The easiest way is probably to create and add all variables, and to create all constraints. Then, for each subproblem you want to 
solve, add the constraints, solve the problem, and delete all constraints again.
To speed things up it should be very easy to record which constraints are in your current problem and then only add and delete the 
constraints that are necessary to get to the next problem.

Tobias


Martin Bergner wrote:
> Hello all,
>
> is there a way to deactivate a constraint during presolving such that a
> solution violating it will be feasible at the end? I can delete
> constraints during presolving (from the transformed problem) but
> solutions violating this constraint will be infeasible. The feasibity is
> checked against the original problem, where the constraint is still
> existing.
>
> I want to solve a lot of similar problems where a subset of constraints
> is disabled in each run. On the other hand, I don't want to keep track
> of the additions and deletions after each try. The problem should
> contain all constraints that are added and only the irrelevant ones
> would be disabled.
>
> Is there a quick way to do that via a presolver or do I need to set up
> the new problem each time from scratch, only including the constraints
> that I want?
>
> Regards,
> Martin
>
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