Mario Ruthmair

Hi Yansong, This is indeed strange. I just tried to reproduce your issue on my side but when I create variables and constraints as you did it in your first block, then the LP file contains no infor...

Yes, if you don't set LB and UB, the default values will be 0 and infinity, respectively. Did you export the model with write()? Which file format did you use? Could you please post the file for th...

Hi Kai, You got already an answer in your support ticket, here is an update on that issue for the community: This is indeed a bug in version 9.1.2 and it will be fixed in the next release later thi...

Hi Amogh, The only difference between the two usages of cbGetSolution() is that you are using it with a single variable while in the callback.py example all variables are queried at once. Both usag...

Hi Juan, As soon as you set up some callback in Gurobi, it will be entered throughout the whole optimization process. But if you immediately leave it based on some condition, e.g., using a Boolean ...

Hi, If you want to only consider integer solutions in your callback, Gurobi has a special "where" value to indicate such cases, i.e., GRB.Callback.MIPSOL, see the callback codes for an overview. Th...

Hi, If you only want to handle product 0 in a special way, then your approach with using a single additional binary variable for each facility is perfectly fine. But you have to link variables q an...

Hi Kai, Yes, this is also what we observed, for some Seed values there are much less solutions than expected, for others it works normally. We are still on this and keep you updated. Best regards,M...

Hi Kai, It seems that you are right, there is something strange going on. We are investigating this case currently at Gurobi. Thanks for pointing us to this! Best regards,Mario

Hi Kai, Setting a different value for parameter MIPFocus usually significantly changes the solution path of the branch-and-bound algorithm in Gurobi. With MIPFocus=1, Gurobi focuses on finding good...