Instances of the multi–item capacitated lot–sizing problem with setup times (MCL) often appear in practice, either in standard form or with additional constraints, but they have generally been difficult to solve to optimality. In MCL demand for multiple items must be met over a time horizon, items compete for a shared capacity, and each setup uses up some of this capacity. In this paper we use ...

Sizing Problem with Setup Times Silvio Alexandre de Araujo Departamento de Matemática Aplicada, Universidade Estadual Paulista, São José do Rio Preto SP, 15054-000, Brazil [email protected] Bert De Reyck Department of Management Science and Innovation, University College London, WC1E 6BT, UK [email protected] Zeger Degraeve Melbourne Business School, University of Melbourne, Carlton VIC...

Production planning with lot-sizing and scheduling in industries where the cleaning times depend on the sequence of the products can be modelled as a mixed integer problem. However, this problem is very hard, and even small instances cannot be solved exactly in a reasonable time. We propose a division of the whole production planning problem into its two subproblems, and to solve each them inde...

We study the minimum concave cost flow problem over a two-dimensional grid network (CFG), where one dimension represents time (1 ≤ t ≤ T ) and the other dimension represents echelons (1 ≤ l ≤ L). The concave function over each arc is given by a value oracle. We give a polynomial-time algorithm for finding the optimal solution when the network has a fixed number of echelons and all sources lie a...

We consider the capacitated lot sizing problem with multiple items, setup time and unrelated parallel machines, and apply Dantzig-Wolfe decomposition to a strong reformulation of the problem. Unlike in the traditional approach where the linking constraints are the capacity constraints, we use the flow constraints, i.e. the demand constraints, as linking constraints. The aim of this approach is ...

This paper considers a single machine capacitated lot-sizing and scheduling problem. The problem is to determine the lot sizes and the sequence of lots while satisfying the demand requirements and the machine capacity in each period of a planning horizon. In particular, we consider sequence-dependent setup costs that depend on the type of the lot just completed and on the lot to be processed. T...

Our research focuses on the development of two cooperative approaches for resolution of the multi-item capacitated lot-sizing problems with time windows and setup times (MICLSP-TW-ST). In this paper we combine variable neighborhood search and accurate mixed integer programming (VNS-MIP) to solve MICLSP-TW-ST. It concerns so a particularly important and difficult problem in production planning. ...

In this paper, we study a multi-echelon uncapacitated lot-sizing problem in series (mULS), where the output of the intermediate echelons has its own external demand, and is also an input to the next echelon. We propose a polynomial-time dynamic programming algorithm, which gives a tight, compact extended formulation for the two echelon case (2-ULS). Next, we present a family of valid inequaliti...