Three regions arising as surrogates in certain network design problems are the knapsack set X = {x [ belong ] [Z^n_+] : [ sum^n_j=1] C_jx_j ≥ b}, the simple capacitated flow set Y = {(y, x) [belong ] [R^1_+] x [Z^n_+] : y ≤ b,y ≤ [ sum^n_j=1] C_jx_j} and the set Z = {(y, x) [ belong ]...

In this paper we give a "personal" survey of the research on the polyhedral approach to lot-sizing problems developed over the last ten years. Most results concern the formulation and reformulations of single-item problems which can be used to tighten the formulation of practical multi-item and...

Much progress has been made in recent years in solving certain classes of production planning problems using mixed integer programming. One of the major challenges is how to make this expertise available and easy to use to the non-specialist and to the practitioners. Here we describe a modeling...

Providing a good formulation is an important part of solving a mixed integer program. We suggest to measure the quality of a formulation by whether it is possible to strengthen the coefficients of the formulation. Sequentially strengthening coefficients can then be used as a tool for improving...

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...