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Crossover LP symmetric solution



1 comment

  • Mario Ruthmair
    Gurobi Staff Gurobi Staff

    Hi Matthijs,

    The barrier algorithm itself rarely ends up with a basic solution (in a corner of the polytope). The first crossover phase (basically simplex) tries to accomplish this, i.e., move the solution towards a corner.

    If symmetry is detected in the model in the presolving phase, the model is first converted to a usually much smaller model avoiding symmetry. But after a solution has been found to the converted model, the solution needs to be unfolded to the original model space. To do that, a few further simplex iterations are needed in this second crossover phase.

    If you are happy with a non-basic solution, you can switch off the first crossover phase via the parameter Crossover=0.

    In some cases, the second crossover phase can be avoided by deactivating symmetry via parameter Symmetry=0, potentially decreasing performance.

    Best regards,


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