Infeasibility question

Answered

Iason Liagkas

• June 14, 2023 21:39

Hello guys, I am modeling a problem relative to traffic equilibrium, and when I add more than a certain number of traffic origin-destination pairs it becomes infeasible. Does this mean that I am reaching the limits of Gurobi since it runs for a certain(large) amount of origin-destination pairs? Is it safe to assume that my theoretical model is feasible since it runs for a large number of origin-destination pairs? The new pairs do not increase the range of coefficients in the model. They are within the existing running range, they are just more of them.       

Kind regards
Iason                                                                                           

Related to

• Infeasible

0

• 

  Jaromił Najman

  Gurobi Staff

  • June 15, 2023 08:09

  Hi Iason,

  Does this mean that I am reaching the limits of Gurobi since it runs for a certain(large) amount of origin-destination pairs?

  No, if a model has a feasible solution then Gurobi should be able to find it at some point in time. This excludes numerically questionable models which or on the edge of (in)feasibility.

  Is it safe to assume that my theoretical model is feasible since it runs for a large number of origin-destination pairs?

  Solving a particular optimization problem does not guarantee that the problem stays feasible for any data input. You would have to think of a more rigorous proof to show that your formulation always yields a feasible point, e.g., by providing a way to always generate a feasible point to your problem from scratch.

  Regarding the infeasibility, did you have a look at How do I determine why my model is infeasible?

  Best regards, 
  Jaromił

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• 

  Iason Liagkas

  • June 15, 2023 21:23

  

  

  

  Thanks Jaromił

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