Originally posted by: srinit34

Hi

I have a branching strategy implemented in my branch callback.

How to stay close to simple branch-and-bound ? I do not want CPLEX to add or remove anything from the model, like cuts or constraints, or variables.

I have used these:

        cplex.setParam( IloCplex.Param.MIP.Strategy.HeuristicFreq , -ONE);
        cplex.setParam(IloCplex.Param.MIP.Limits.CutPasses, -ONE);
        cplex.setParam(IloCplex.Param.Preprocessing.Presolve, false);

That already looks good. Are you seeing unexpected things? You may also want to disable dynamic search if you want to have "plain old B&B". Other things you may explicitly want to disable is node presolve and probing.

Originally posted by: srinit34

Thank you for comment.

I already have a branch callback so it is single thread traditional.

I have added:

        cplex.setParam(IloCplex.Param.MIP.Strategy.PresolveNode, -ONE);
        cplex.setParam(IloCplex.Param.MIP.Strategy.Probe, -ONE);

I also tested with MIP emphasis set to best-bound, but for one MIP (p6b) I saw that CPLEX is unable to solve the MIP to completion even after several days.

But I guess that is not really unexpected.

At least it is not surprising that the running time explodes. You are disabling everything that makes the solution strategy reasonable in practice :-)

For model p6b you can for example see, that in a regular solve almost all feasible solutions found come from heuristics. Also, on this model cuts quickly raise the best bound from something around -231 to something around -70 (the optimal solution being -63). With these two features disabled you have to find all these things by enumeration and that can of course take quite a while.

Is strong branching allowed in your framework? That may improve running time a little.