Decision Optimization

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CPLEX terminate abnotmally in a large problem

  • 1.  CPLEX terminate abnotmally in a large problem

    Posted 08/28/08 04:50 AM

    Originally posted by: SystemAdmin


    [mangotree said:]

    Hello everybody,

    I'm trying to solve a large MIP problem with >~100k binary variables. We got a strange result in log file:
    The cplex returning status is 2 (solved)
    However,
    The objective function field show "Infeasible" and MIP gap is "0.00%"
    We check the cplex solution, it seems to be a feasible one...

    What could be the issue that CPLEX terminate so fast? ill-condition for A matrix?

    Please see the attachment!


    #CPLEXOptimizers
    #DecisionOptimization


  • 2.  Re: CPLEX terminate abnotmally in a large problem

    Posted 08/28/08 01:18 PM

    Originally posted by: SystemAdmin


    [Sylvain said:]

    In your log, we can see that Cplex finds a solution at the root node and then proves infeasibility of the remaining problem (probably after adding more cuts).
    It looks normal.
    Regarding the speed, in a few cases the LP relaxation of a MIP problem returns a solution where all binary variables have a value of 0 or 1 (and not a fractional value as expected). In that case, no search is needed and the problem is solved at the root node.
    Maybe you could give more information about your problem to check if you are in this case.
    #CPLEXOptimizers
    #DecisionOptimization


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