[Scip] SCIPchgLhsLinear()

[Gerald Gamrath]

Dear Hélène,

the left hand side is changed globally, and I must admit I'm not sure
this is really meant to be used during the branch-and-bound search.

Why can you update the left hand side during the search?

I would suggest the following: Transform your inequality into an
equality by introducing a slack variable, instead of sum a_i x_i >= lhs,
write it as sum a_i x_i - s = lhs, with s being a non-negative variable.
During the search, you can then locally increase the lower bound of s,
which corresponds exactly to increasing the left hand side of the
constraint (I suppose you want to increase it, decreasing it would widen
the search space which you should not do during the search).

Best,
Gerald

On 08.11.2013 11:05, Hélène Toussaint wrote:
> Dear all,
>
> I use the function SCIPchgLhsLinear() to update some constraints
> during a Branch and price algorithm. Could you please tell me if the
> left hand side of the constraint is changed locally (in the current
> node and its children only) or globally ? If it is changed globally
> there is a way to changed it locally ?
>
> Best regards,
> Hélène
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