Decision Optimization

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  • 1.  Help VRPTW-Python API

    Posted Mon November 16, 2020 01:48 PM
    I'm trying to solve the VRPTW using python however I'm getting no result (infeasible solution). Could anybody provide some help? attached are the data file I'm using and the jupyter notebook. So far I know the problem is feasible but maybe I'm missing something

    Agustin Guerra


  • 2.  RE: Help VRPTW-Python API

    IBM Champion
    Posted Mon November 16, 2020 05:44 PM
    Assuming that your problem is actually feasible, try the following.
    1. Make up a feasible solution (a set of routes that satisfy all constraints, including time windows). It does not matter how poor the objective value is, just that it is feasible.
    2. In your model, fix all the variables at the corresponding values (by setting lower bound = upper bound = value).
    3. Try to solve your modified model. Presumably CPLEX will declare it infeasible.
    4. As CPLEX for an irreducible infeasible subset (IIS). If your candidate solution really is feasible, at least one of the constraints in the IIS (other than the bounds you set) must contain an error.

    Paul Rubin
    Professor Emeritus
    Michigan State University

  • 3.  RE: Help VRPTW-Python API

    Posted Tue December 01, 2020 11:18 AM
    That makes sense many thanks for the suggestion I'll try it.

    Agustin Guerra