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Debugging wrong MIPSOL_OBJBND



  • Barak Gross
    First Question
    First Comment

    BTW, I tried the following:
    * Saving all lazy constraints
    * Created a constraint : OBJ <= CORRECT BOUND
    * Found n - the first time that adding the OBJ constraint and the first n lazy constraint became infeasible
    * Ran IIS on the infeasible instance. But this part is the hard one, it takes A LOT of time (more than 20K seconds) and it seems like I need at least 600 inequalities... Which means that even when (and if) it terminates, I wont be able to debug what exactly is wrong with the lazy constraints.

  • Tobias Achterberg
    Gurobi Staff Gurobi Staff

    What if instead of adding the OBJ <= CORRECT BOUND constraint you fix all the variables to their optimal solution values, add the n constraint that invalidated this solution and then calculate an IIS? This should very quickly yield a single constraint that is invalid for your solution.





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