Tobias Achterberg

When you have a minimization problem with optimal value 100, then at any point in time the incumbent objective value will be primalbound >= 100 while the objective bound will be dualbound <= 100 Wh...

Uhh... I fear that in this case you are out of luck. I doubt that we will want to increase the complexity of our parameter settings and combinations (that we have to document and also to test) for ...

A MIP start is a starting solution that is checked at the beginning of a solve whether it is feasible. If so, it will be used as an incumbent solution to speed up the optimization process. This MIP...

I think that you have just hit a small quirk in our callback behavior at the root node. Namely, the solution *is* accepted, but at the time the next log line directly after the callback invocation ...

Hi Andreas and Jan, my guess is that you are talking about storing the solving state of a MIP solve to a file, i.e., the full search tree plus all the additional information like cuts and pseudo co...

What if instead of adding the OBJ <= CORRECT BOUND constraint you fix all the variables to their optimal solution values, add the n constraint that invalidated this solution and then calculate an I...

With the "SetSolution()" call you are modifying the user solution that is stored in the callback object. So, you can, for example, call SetSolution() for each variable individually to specify all v...

Unfortunately, this is not how gurobipy and Gurobi work. The Python API in gurobipy is, by design, just a layer around the C API of Gurobi. And the C API does not understand the concept of matrix v...

I finally found the cause of the issue. It actually has nothing to do with the MIP scenario analysis feature. It is a bug in handling SOS constraints with continuous variables inside the symmetry d...

No. Dual solutions (including shadow prices) are only defined for continuous models. They don't make any sense for integer models. If you are interested in sensitivity analysis for integer models, ...