Decision Optimization

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  • 1.  LP relaxation of the root node

    Posted Wed August 23, 2023 09:44 AM

    I want to get the solution for the LP relaxation of the root node so I can check if there is any cut that I can add to the original MIP problem. 

    However I am not sure there is a straight forward way for doing that in cplex and I am a bit indecisive between these two options:

    If I go with the first option I know that setting the parameter to 0 will prevent from applying the extra cut to the root node but still I am not sure if that will be the equivalent to the LP relaxation solution of the root node. 

    As for the second option, it will relax the root node but how we can ask CPLEX to stop running right after that step and return the solution to us?


    soheyl zehtabiyan

  • 2.  RE: LP relaxation of the root node

    IBM Champion
    Posted Sun August 27, 2023 12:17 PM

    It's not entirely clear what you want to do. Do you want the LP relaxation of the original root node (before CPLEX adds any presolve cuts) or the LP relaxation including presolve cuts? If the former, you could just relax the original model to an LP and solve it.

    Paul Rubin
    Professor Emeritus
    Michigan State University