Originally posted by: Guerlain

I have a problem with my VRP 

the beginning and the end of the tour must be in the supplier depot so I should have something like this in every tour (1-3-..-5-1) but I've usually something like this (1-5-..2-1) and (6-4-6) could you please help me the code is bellow.

I cannot tell which (if any) constraints in your model are responsible for subtour elimination.

Originally posted by: Guerlain

In my model the subtour elimination constraints are :

forall(i,j in 2..n: j!=i, t in 1..t, k in Vehicles)
u[i][k][t]- u[j][k][t]+((n-1)* x[<i,j>][k][t])<= Cap_Veh[k][t] - Transf[j][k][t]; 
 
forall(i in 2..n, t in 1..t, k in Vehicles)
1 <= u[i][k][t] <= n-1;

If the first constraint above is supposed to be the Miller-Tucker-Zemlin subtour elimination constraint, bear in mind that in M-T-Z the right hand side of the constraint is one less than the coefficient of the arc crossing variable (your x). So with x multiplied by n-1 on the left, the right side should be n-2. If Cap_Veh[k][t] - Transf[j][k][t] comes out greater than that, it will allow a subtour to sneak in.

Originally posted by: Guerlain

Thanks now it work perfectly 

Originally posted by: sophieTSP

I am trying to solve an extention of the traveling salesman problem and I do not know how to write on OPL cplex, the constraint of elimination of the subtours, I treat the TSP probabilist, (of the customers with present pi). decision with three variables, i, j for clients and k for the scenario:

the subtraction elimination constraint for the classical traveling salesman  problem is as follows: at xij's place, i have xijk now

// Subtour elimination constraints.
     forall (s in subtours)
         sum (i in cities: s.subtour [i]! = 0)
            x [minl (i, s.subtour [i]), maxl (i, s.subtour [i])]
            <= s.size-1;
           
  };
  how could I add the 3rd index on this constraint?

Is this related to your question here? I think I may have covered your question in one of my replies. I think that because in each snapshot you have a different set of cities, you will have to consider a different set of subtours for each snapshot. I have posted some code there that does this. Please come back if that does not answer your question.