Originally posted by: 4D3U_Andrea_Peano

Hello,

I would implement a branching policy by adding a set of constraints, rather than by changing the bounds of a single variable.

The BranchCallback has this method:

protected IloCplex.NodeId makeBranch(IloRange rng, double objestimate,java.lang.Object data)

So, I implemented a branch callback that uses it. In particular, I defined a new range by means of the main CplexModeler instance (the one used to build the main MILP model):

IloRange r=model.addEq(expr, 0.0);

Is that the right way to make this type of branching policy? Unfortunately, I did not find any example about the branching on ranges.

Thank you,

Andrea

EDITED:

One should use the method model.eq, instead of model.addEq, am I right?

No, that is wrong. What you need to do in your callback's main() function is something like this:

protected void main() throws IloException {
   makeBranch(cplex.eq(expr, 0.0), getObjValue());
}

That will create a new branch that is defined by the additional constraint expr==0. Note that I used function eq() and not function addEq()!

Originally posted by: 4D3U_Andrea_Peano

Thank you Daniel.

Now it works very well!