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limiting number of solution and getting rapid solutions

  • 1.  limiting number of solution and getting rapid solutions

    Posted Thu March 04, 2021 04:11 PM
    Dear, I want to keep only one or two best solutions instead of 20 or more solutions in cplex. How to set this.
    Also, how can I set relaxation to get solutions faster.

    Best Regards

    Ismail

    ------------------------------
    Muhammad Ismail
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    #GlobalAIandDataScience
    #GlobalDataScience


  • 2.  RE: limiting number of solution and getting rapid solutions

    Posted Fri March 05, 2021 02:58 AM
    Hi

    the CPLEX / Decision Optimization community : ibm.biz/DOcommunity

    For the solution pools question let me change a bit the example from https://github.com/AlexFleischerParis/zooopl/blob/master/zooseveral.mod


    I add


     
    cplex.solnpoolcapacity=2;
cplex.solnpoolreplace=1;

    So I use

        int nbKids=300;
    float costBus40=500;
    float costBus30=400;
     
    dvar int+ nbBus40;
    dvar int+ nbBus30;
     
    minimize
     costBus40*nbBus40  +nbBus30*costBus30;
     
    subject to
    {
     40*nbBus40+nbBus30*30>=nbKids;
    }

    execute
    {
    writeln("nbBus40 = ",nbBus40," and nbBus30 = ",nbBus30," and the cost is ",costBus40*nbBus40  +nbBus30*costBus30);
    }

     main {
    cplex.solnpoolintensity=4;
    cplex.solnpoolcapacity=2;
    cplex.solnpoolreplace=1;

        thisOplModel.generate();
        cplex.solve();
        if (cplex.populate()) {
          var nsolns = cplex.solnPoolNsolns;
          
          
          writeln("Number of solutions found = ",nsolns);
          writeln();
          for (var s=0; s<nsolns; s++) {
            thisOplModel.setPoolSolution(s);
            thisOplModel.postProcess();
          }
        }
    }​


    which gives

    Number of solutions found = 2

nbBus40 = 6 and nbBus30 = 2 and the cost is 3800
nbBus40 = 3 and nbBus30 = 6 and the cost is 3900


    ------------------------------
    [Alex] [Fleischer]
    [EMEA CPLEX Optimization Technical Sales]
    [IBM]
    ------------------------------

    Original Message