I was just thinking that all these 3 constraints can be written as one
"Torsten" wrote in message <firstname.lastname@example.org>... > Because you substitute x_ik*x_jk = min(x_ik,x_jk) , I think you will need z_ijk: > z_ijk <= x_ik > z_ijk <= x_jk > z_ijk >= x_ik + x_jk - 1
Good point Torsten. Theoretically, I would need to index z over k but from other constraints I also know that there may be at most one k for which z_ijk=1 and I don't need to know the detailed information which k it is, but only the indication whether it happens at all. Would indexing z_ij be correct in that case? It's important to me to limit the size of the variables as well.