[Scip] Controlling if the linear constraint's row is in the LP

[Jakob Witzig]

Hi Jens,

I'm very sorry for the late response, we are currently busy with the 
upcomming SCIP release.

It is not possible to controle/remove constraints within the B&B tree if 
they are already in the LP. If you add a dominating constraint during 
the presolving SCIP will detect the dominance and remove/disable the 
dominated constraint.

Best
Jakob

Am 20.05.2015 um 11:09 schrieb Jens Leoff:
> Hi,
>
> I have a branch & price algorithm and branch by adding constraints.
> It can happen that I introduce 2 linear constraints (modifiable) that 
> have, and always will have the same coefficients and variables, but 
> different left hand sides.
> So for example I have
> a*x >= and
> a*x >=
> Thus the first constraint is dominated by the second one in that part 
> of the B&B tree.
>
> What I currently do is adding both as linear constraints, and my LP 
> contains a row for each of the constraints as well.
>
> I want to remove the lp row of the dominated constraint in that part 
> of the B&B tree.
> I tried to disable the weaker constraint, to delete it locally, to set 
> it removable for lp cleanup... but non of these seem to bring the 
> desired effect.
> How can I control which rows are in the LP?
>
> Best regards,
>     Jens
>