Decision Optimization

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  • 1.  OPL CP No solution available, cannot process.

    Posted Mon July 06, 2020 03:32 AM
    Hi everyone.
    Recently I am working on a scheduling problem using Constraint programming (CP) in OPL. In the log file, 39 solutions are found but finally it shows no solution available. The log data is shown below.
    Can anyone can help to explain why? Thanks a lot.

    ! ----------------------------------------------------------------------------
    ! Search terminated by limit, 39 solutions found.
    ! Best objective : 315.935
    ! Number of branches : 5,056,241
    ! Number of fails : 1,809,900
    ! Total memory usage : 238.2 MB (235.1 MB CP Optimizer + 3.2 MB Concert)
    ! Time spent in solve : 180.22s (180.17s engine + 0.04s extraction)
    ! Search speed (br. / s) : 28,062.3
    ! ----------------------------------------------------------------------------
    No solution available, cannot process.

    END

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    HUI ZHAO
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    #DecisionOptimization


  • 2.  RE: OPL CP No solution available, cannot process.

    Posted Mon July 06, 2020 12:06 PM
    Hi,

    can you share your model and data so that some other user could try ?
    Do you rely on some flow control ?

    regards

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    ALEX FLEISCHER
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  • 3.  RE: OPL CP No solution available, cannot process.

    Posted Thu July 09, 2020 01:28 AM
    Hi Alex,
    Thank you for replying me promptly. 
    I am sorry that I cannot share the model and data since they are confidential. 
    1) What kind of flow control do you mean? Do you mean some function controlling the sequence in constraint programming? If so, yes, I have used some basic functions of constraint programming in the model, including endBeforeStart, presenceOf, span, alternative, noOverlap. 
    2) In the log I shown in the first message, my understanding is that the 39 found solutions are actually feasible solutions and the solver will provide the solution with the best objective value as the final solution. If my understand is correct, then we should not see the No solution available, cannot process in the end.
    Can you help to confirm? 
    Thank you so much.
    Looking forward to your reply.

    Best Regards,
    Zhao Hui

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    HUI ZHAO
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  • 4.  RE: OPL CP No solution available, cannot process.

    Posted Thu July 09, 2020 01:48 AM
    Hi,


    about flow control, I meant do you have a block main in your .mod or only preprocess, subject to and then postprocess ?

    Basic example of flow control : https://github.com/AlexFleischerParis/zooopl/blob/master/zooflowcontrolincremental.mod

    regards

    ------------------------------
    ALEX FLEISCHER
    ------------------------------



  • 5.  RE: OPL CP No solution available, cannot process.

    Posted Thu July 09, 2020 01:56 AM
    Hi Alex,
    I do not have a main block in my .mod file. My .mod file only has data preprocess, minimize, subject to, and then postprocess. 
    Thank you.

    Best Regards,
    Zhao Hui

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    HUI ZHAO
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  • 6.  RE: OPL CP No solution available, cannot process.

    Posted Thu July 09, 2020 04:20 AM

    Hello, can you tell me which version of CPLEX Studio you are using?

    Regards,



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    Paul Shaw
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  • 7.  RE: OPL CP No solution available, cannot process.

    Posted Thu July 09, 2020 04:24 AM
    Hi Paul,
    Thanks for reply.
    My CPLEX studio version is 12.6.0.0.
    Thank you.

    Best Regards,
    Zhao Hui

    ------------------------------
    HUI ZHAO
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  • 8.  RE: OPL CP No solution available, cannot process.

    Posted Fri July 10, 2020 05:11 AM
    It seems that this problem has been solved in a more recent version. 12.6 is rather old, can you update to the most recent (12.10) and tell us if the problem is still there  ?

    Thanks


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    --
    Philippe Refalo
    IBM ILOG CP Optimizer
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  • 9.  RE: OPL CP No solution available, cannot process.

    Posted Sun July 12, 2020 09:17 PM
    Hi Philippe Refalo,
    Thanks for your reply.
    We will try to update the version and let you know if that problem is still there later.
    Thank you.

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    HUI ZHAO
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