We study further a problem that has arisen recently in the design of telecommunications transmission networks at France Telecom. Given a set of centers in a city of conglomeration linked together on a ring architecture, given the expected demands between the centers and an essentially unlimited...

BC-PROD is a prototype modelling and optimization system designed and able to tackle a wide variety of the discrete-time lot-sizing problems arising both in practice and in the literature. To use BC-PROD, the user needs to formulate his/her problem as a mixed integer program using XPRESS-MP's...

In spite of the remarkable improvements in the quality of general purpose mixed integer programming software, the effective solution of a variety of lot-sizing problems depends crucially on the development of tight formulations for the special problem features occurring in practice. After...

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

We study the convex hull of the continuous knapsack set which consists of a single inequality constraint with n non-negative integer and m non-negative bounded continuous variables. When n = 1, this set is a slight generalization of the single arc flow set studied by Magnanti, Mirchandani, and...

A separation heuristic for mixed integer programs is presented that theoretically allows one to derive several families of "strong" valid inequalities for specific models and computationally gives results as good as or better than those obtained from several existing separation routines...