The IloLeLex function returns a constraint which maintains two arrays to be lexicographically ordered.

More specifically, IloLeLex(x, y) maintains that x is less than or equal to y in the lexicographical sense of the term. This mean that either both arrays are equal or that there exists i < size(x) such that for all j < i, x[j] = y[j] and x[i] < y[i].

Note that the size of the two arrays must be the same.