cplex error 1217 :no solution exists

[vivianx]

Hi,
I am trying to solve a capacitated vehicle routing problem. I created a model on gams but i gave cplex error 1217.

I changed some parts to fix this issue but still i keep getting the same issue and i'm stuck on this part. What exactly is the cause of the problem and how can i fix it?

Here is my code

deneme4.gms

(6.6 KiB) Downloaded 51 times

thank you for your help in advance.

[Fred]

Your model is infeasible. So there is no feasible point to all the constraint to have specified. When Cplex returns "integer infeasible" a good first step is often to solve the model as RMIP, i.e. solve the resulting LP you get when relaxing integrality requirements for the discrete variables. Turns out that the RMIP is also infeasible. This state of the optimization model is in general not a bug or problem. It is one of the possible theoretic outcomes of an optimization run: optimal/infeasible/unbounded.
The real work is to figure out where the infeasibility comes from. There is no single way of doing this. It very much depends on your knowledge and understanding of the original problem and its implementation as a model. You can for example ask Cplex to provide you with the smallest set of constraints that are infeasible via the iis option.
This gives me two conflicting constraints for your model.

Code: Select all

Number of equations in conflict: 2
upper: sub2(2,2) < -1723
upper: sub3(2,v3) < 80

Number of variables in conflict: 0

Maybe this helps you to get to the bottom of the issue.

Best,
Fred