Originally posted by: mkadem

Hello,

I am using Concert for C++  and I want to fix some decision variables inside a callback.

In fact, i'm using a method (based on a graph) that could predict  the correct values of a set of unfixed binary variables after taking into account the decisions of CPLEX (the fixed variables).

I'm wondering if it is possible for me to use a control callback  to fix these variables, which will be  active only when processing nodes of this subtree.

thank you for the help...

regards,

Two callbacks come to mind:

1. You can add the additional fixings in a branch callback (add the fixings to each child node the callback creates).
2. You can add the additional fixings in a lazy constraint callback as local constraints (using the callback's addLocal() method).