We study different extended formulations for the set X = {x E Zn | Ax = Ax0} in order to tackle the feasibility problem for the set X+ = X N Zn+. Here the goal is not to find an improved polyhedral relaxation of conv(X+), but rather to reformulate in such a way that the new variables introduced...

We consider both branch-and-cut and column generation approaches for the problem of finding a minimum cost assignment of jobs with release dates and deadlines to unrelated parallel machines. Results are presented for several variants both with and without Constraint Programming. Among the...

We consider the single item lot-sizing problem with capacities that are non-decreasing over time. When the cost function is i) non-speculative or Wagner-Whitin (for instance, constant unit production costs and non-negative unit holding costs), and ii) the production set-up costs are...