[SCIP] SCIPmarkDoNotUpgradeConsLinear

Luciana Garcia Richter lugrichter at gmail.com
Fri Apr 8 14:05:59 CEST 2016


Hi Gerald,

Thanks for the quick response. You are right, for this example I have
forgot to mark the constraint as modifiable. Thanks a lot.

Regards,
Luciana

On Thu, Apr 7, 2016 at 8:26 PM, Gerald Gamrath <gamrath at zib.de> wrote:

> Dear Luciana,
>
> there is the method SCIPconsAddUpgradeLocks() in pub_cons.h now which
> allows you to disallow upgrading of constraints. Sorry, it seems that we
> forgot to document this replacement in the change log.
>
> By the way: If you need dual values of a constraint in column generation,
> you probably want to possibly add variables to that constraint? In that
> case, the constraint should be marked as modifiable when creating it, and
> in this case, no upgrade should happen. Please be sure that you mark all
> constraint as modifiable to which variables may be added during solving,
> because otherwise, they may do reductions based on the assumption that the
> constraint won't change.
>
> Best,
> Gerald
>
>
> Am 08.04.2016 um 01:07 schrieb Luciana Garcia Richter:
>
> Hi,
>
> I was looking an old version of scip which includes function
> SCIPmarkDoNotUpgradeConsLinear. But later I realize this function was
> removed in the last version. I didn't found any comment about this in the
> change log.
>
> There is any reason this function was removed? There is any other way to
> force scip to maintain specific constrains?
>
> I'm doing a column generation algorithm, and I need some constraint not
> being removed because I need to get the dual value of them (if they get
> removed I get a zero when I ask for dual value).
>
> Thanks in advance,
> Luciana
>
>
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