Hello
I know, the title of my posting sounds "crazy" but this is what happens.
I solve a MIP Problem (scheduling) using GAMS/CPLEX to optimality. The solver returns the optimal solution (I know that this is the optimal one, I am using a test problem).
Now, when I resolve the problem by fixing a subset of the variables to their optimal values, CPLEX claims that the problem is infeasible.
Has anyone any hints of what could cause such a behaviour of the solver? What should I look for, when rying to fix the problem?
Cplex generates optimal solution but then declares it to infeasible
Re: Cplex generates optimal solution but then declares it to infeasible
Hi Nikou,
Can you share an example, so other forum users can reproduce the observed behavior.
Would also be interesting to know which version you are using.
Best,
Fred
Can you share an example, so other forum users can reproduce the observed behavior.
Would also be interesting to know which version you are using.
Best,
Fred
Re: Cplex generates optimal solution but then declares it to infeasible
I am sorry I can't give an example now. The model has become too complex, and I have to admit a real mess.
I will try to sort out what happens. I suppose the problem has to do with the use of small numbers and BigM constraints.
I will try to sort out what happens. I suppose the problem has to do with the use of small numbers and BigM constraints.
Re: Cplex generates optimal solution but then declares it to infeasible
False alarm! There is nothing wrong with the solver. I did make a mistake in the input data!