Mario Ruthmair

Hi Bence, Probably it is more intuitive to introduce binary node variables y_vars[i] that are 1 if node i is visited and 0 otherwise. Then, you can easily state your objective function as objective...

Hi Bence, There is a lot of literature on modeling the orienteering problem and its variants, see for example this EJOR paper. Do you observe any problems with your model and implementation? You sh...

Hi Pedro, You have to tell both Slurm and Gurobi how many threads you want to use. For Slurm it is important to know how many threads a job will use to ensure a correct resource scheduling for all ...

Hi Roos, Ok, so you want to solve a pickup-and-delivery problem with 3 commodities, each with a dedicated source and target node. You have two vehicles, each with capacity 6. The model is called PD...

Hi Thu, What exactly is your problem with constraints (4)? Could you please provide more details? Best regards,Mario

Hi Roos, Your linearization of the max and min terms looks ok. I guess "qi" can get negative, otherwise the max and min terms would not make sense. What exactly does not work? Could you show the re...

Hi Jiongjian, Regarding your MIP start question: Every change in parameters or MIP starts can potentially have a large effect on the solver runtime due to different solution paths in presolving, br...

Hi Jiongjian, my answer above refers to your first message. The approach used there should work, I just tried it. Could you please show more details of your Gurobi output? Best regards,Mario

Hi Jiongjian, just to be sure to understand your workflow: You solve a MIP and by setting the \(\texttt{SolFiles}\) parameter you write all solutions that come up during the solution process to a ...

Hi Lorenzo, quadratic equality constraints are never convex. The feasible set usually contains discrete points that are not connected and thus the set is non-convex. Best regards,Mario