HAOXING OUYANG

But the symmetry breaking constraint is not a necessary constraint in my model, the purpose of adding it is to accelerate the speed of model solving. Do I still need to verify the infeasibility of ...

Hi Riley, Yes sir, your understanding is correct. My advice is to add everything as normal constraints, so that you get an infeasible model, then follow our guide How do I determine why my model i...

Hi Riley, I am not split the symmetry breaking constraints into lazy constraints and user cut. Certainly, I just add the constraint (34) as user cut. And it is infeasibe when I just add it to my mo...

Hi Riley, There seems to be a slight deviation: (1) You have some constraints which can be used to break symmetry and are not necessary for a correct solution. When you add all of these as normal ...

Hi Riley, Thanks for your reply! I made modifications based on your code. After testing, the code for User Cut is feasible. Now what makes me confused is: When I use User Cut or Lazy Constraints al...

I forgot to mention that in my code, "instance. nodesNum" includes node 0 and node n+1 (both of which are the same depot). This is a bit different from the constraints(34)-(35) in the picture.

Hi Riley, Thank you for your reminder! But I'm facing another problem now. Could you please help me take a look? What I want to solve is a Vehicle Routing Problem, using three-index variables X[i][...

Hi Riley, Thank you very much for your reply! Best, Haoxing

Hi Riley, After listening to your advice, I set: model.set(GRB.IntParam.Seed, 2000000000); I tested it with different examples, and in some cases, the solution speed using the callback method is in...

Hi Riley, Yes, I mean solving the original model is faster than using callback method.