Decision Optimization

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Infeasible problem Conflict refiner doesn't work

  • 1.  Infeasible problem Conflict refiner doesn't work

    Posted Tue October 04, 2011 03:01 PM

    Originally posted by: sophiejuin


    Hello,

    I am working with cplex and c++ together.

    I built a MIP(about 70 binary variables), and I used several logical constraints.

    The problem is that the program works well with some datasets. But for some particular ones, it's infeasible.

    I tried to solve the problem by looking at the linear program I exported, but no result.

    I tried to use conflict refiner, but it didn't give me any suggestion.

    Any one know the possible reasons for this weird problem?

    Thanks in advance.
    #CPLEXOptimizers
    #DecisionOptimization


  • 2.  Re: Infeasible problem Conflict refiner doesn't work

    Posted Wed October 05, 2011 09:34 PM

    Originally posted by: EdKlotz


    > sophiejuin wrote:
    > Hello,
    >
    > I am working with cplex and c++ together.
    >
    > I built a MIP(about 70 binary variables), and I used several logical constraints.
    >
    > The problem is that the program works well with some datasets. But for some particular ones, it's infeasible.
    >
    > I tried to solve the problem by looking at the linear program I exported, but no result.
    >
    > I tried to use conflict refiner, but it didn't give me any suggestion.
    What exactly do you mean when you say the conflict refiner didn't give you any suggestion?
    Do you mean that CPLEX claimed the model was infeasible when you optimized, but the
    conflict refiner said it was feasible? Or did the conflict refiner give you a conflict,
    but the size of the conflict was too large to enable straightforward assessment of the
    cause of the infeasibility?

    Can you reproduce the infeasibility by reading in the exported linear program into
    interactive CPLEX? If so, please post the output when you try to run the conflict
    refiner afterwards.

    >
    > Any one know the possible reasons for this weird problem?
    >
    > Thanks in advance.
    #CPLEXOptimizers
    #DecisionOptimization


  • 3.  Re: Infeasible problem Conflict refiner doesn't work

    Posted Thu October 06, 2011 12:06 PM

    Originally posted by: sophiejuin


    CPLEX gave me the following message:
    "Concert exception caught: CPLEX Error 1720: Conflict detection could not reproduce previously found infeasibility"
    But someone did find the conflict with cplex 12.3 while I'm using cplex 11.1. I guess it maybe the reason.

    Fortunately, I have solved the problem with the help of the people here. Sorry I posted my message twice. If you are interested, please find the discussion:

    https://www.ibm.com/developerworks/forums/thread.jspa?messageID=14690350&#14690350
    #CPLEXOptimizers
    #DecisionOptimization