[Scip] How to add linear constraints during solve s.t. these survive complete restart?

[Marc Pfetsch]

Hi Matthias,

as far as I see, this is currently only possible if you add the 
constraint if SCIP is in the problem stage, i.e., if you already freed 
the solving data. Thus, you would need to store the data of the cuts and 
then create the constraints after freeing the transformed problem. Of 
course, you would then need to use the original variables (and not the 
transformed ones).

If you want to proceed this way, you need to establish a way of storing 
the information and making sure that the data is not freed if you free 
the transformed problem (this should not be too hard). But if you have 
written this part of code, it seems that it would be no problem to 
separate over this data during an ordinary run. However, adding the 
constraints before the solution would include it in the presolving process.

Best

Marc

On 07/04/2014 04:05 PM, Matthias Walter wrote:
> Dear list,
>
> I solve a certain problem very often and (using a constraint handler) I
> generate linear constraints during the solving process. What I want is
> that after I free the transformed problem/solve data, change some
> variable objectives and call solve again, these linear constraints are
> available so I don't need to separate them again. I tried to create real
> constraints within the enforcement/separation callbacks (and not just
> add rows) but that didn't help them to survive a new start.
>
> Is this possible with SCIP, e.g., by adding the constraints w.r.t. the
> original variables and not their transformed counterparts?
>
> Best regards,
>
> Matthias
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