Decision Optimization

Decision Optimization

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  • 1.  Subtour Elimination

    Posted 04/25/15 04:24 PM

    Originally posted by: jarchit52


    I want to implement subtour elimination in Vehicle Routing Problem(constraints of capacity and distance). 
    I have written this constraint but still subtours appear in the solution.

    forall(i in 1..N) forall(j in 1..N) forall(k in VEHICLE)
      subtour[i,j,k] : U[i,k] - U[j,k] + cap*X[i,j,k] + (cap - d[i] - d[j])*X[j,i,k] <= cap - d[j];

     

    cap = capacity of vehicle

    d[i] = demand of customer 1

    Please help

     

     


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  • 2.  Re: Subtour Elimination

    Posted 05/18/15 01:19 AM

    These pure OPL questions are better asked on the OPL Forum.

    Questions about how to write subtour elimination constraints have been asked many times here. You may want to search the CPLEX Forums for answers.

    At first glance it looks odd to me that you don't have any sort of powerset construct in your formulation. Wouldn't you need that to eliminate all potential subtours?


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