# Mario Ruthmair

Gurobi Staff
• Total activity 109
• Last activity
• Member since
• Following 0 users
• Followed by 1 user
• Subscriptions 38

## Activity overview

Latest activity by Mario Ruthmair
• Mario Ruthmair commented,

Hi Ashrafur, The lower and upper bounds to variable L(r,i) are basically defined by constants (vehicle capacity Q(r) and customer demand q(i)), right? So the min and max operators can be applied in...

• Mario Ruthmair commented,

Hi Dilip, Yes, this looks correct. Mario

• Mario Ruthmair commented,

Hi Dilip, Did you try it and analyze the solutions? 2nd model: I do not think that it works since you just added a single constraint, instead of one constraint for each vehicle k. 12 days ago you a...

• Mario Ruthmair commented,

Hi Dilip, We already discussed how you can model a min-max objective function, see the messages above. So, could you be a bit more precise about what does not work with the approach I suggested? Be...

• Mario Ruthmair commented,

Hi Dilip, I am not sure if I can follow your last messages. Do you still have problems? Best regards,Mario

• Mario Ruthmair commented,

Hi Dilip, I can spot two issues: I think your depot is 0 according to the definition of "customers" and "total", but in your formulation you assume customer 1 to be the depot. In the last set of c...

• Mario Ruthmair commented,

Hi Dilip, Your code for this particular model part looks correct, although you might write the quicksum in a more efficient way: m.addConstr(quicksum(x[i, j, k]*dist_matrix[i,j] for i in total for...

• Mario Ruthmair commented,

Hi Dilip, You can reformulate the min-max objective by introducing a single additional continuous variable z, and then move the tour distance calculation to a set of constraints, i.e.: $$\min z$$ \$...

• Mario Ruthmair commented,

Hi Lorenzo, We had a discussion with our developers and the following is the answer my colleague Silke already told your colleague Luca. I just add it here for completeness: "The exception is ignor...

• Mario Ruthmair commented,

Hi Marco, This request is handled in our ticketing system. You should have already received a notification. Best regards,Mario