Solving a TSP using lazy constraints

2 comments

  • Dear Marcel,
    now I got it with the subtour elimination constraints. The CVRP example was very helpful. But now two errors are shown to my and I don’t know how to solve this problems. The errors are:
    1. The element ‘0’ in set “Kminus_i_gleich0” is not in its range set “Set_of_all_nodes”.
    2. The element ‘0’ in set “Set_of_all_nodes_i_gleich0” is not in its range set “Set_of_all_nodes”.

    But I defined the Set_of_all_nodes like that:
    Definition:ElementRange(0,Numberofcars)
    where Numberofcars is a Parameter
    I defined Kminus_i_gleich0 like that:
    Subset of Set_of_all_nodes
    Definition::ElementRange(0,0)
    I defined Set_of_all_nodes_i_gleich0 like that:
    Subset of Set_of_all_nodes
    Definition::ElementRange(0,0)

    So I don’t understand why 0 isn’t in the range of Subset_of_all_nodes although I defined it like that. Thank you a lot in advance for your help!
    Best regards,
    Mareike

    • I am not sure what is going on; to find out I would need your project. It seems that the sets Kminus_i_gleich0 and Set_of_all_nodes_i_gleich0 only contain one element, namely 0. Instead of that set you can also represent that element directly, e.g. x(‘0’), or use an element parameter.

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