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2002


    

Session MB6 - Conception de réseaux / Network Design

Day Monday, May 05, 2003
Room Nancy et Michel-Gaucher
President Bernard Gendron

Presentations

14:45 Learning Strategies for Fixed Charge Capacitated Multicommodity Network Design
  Ilfat Ghamlouche, Université de Montréal, Informatique et recherche opérationnelle, C.P. 6128, Succ. Centre-ville, Montréal, Québec, Canada, H3C 3J7
Teodor Gabriel Crainic, Université du Québec à Montréal, C.R.T., C.P. 6128, Succ. Centre-ville, Montréal, Québec, Canada, H3C 3J7
Michel Gendreau, Université de Montréal, C.R.T. et Informatique et recherche opérationnelle, C.P. 6128, Succ. Centre-ville, Montréal, Québec, Canada, H3C 3J7

We propose a method based on search guidance structures to solve the fixed charge capacitated multicommodity network design problems. In particular, adaptative memories are used to identify meaningful fragments of solutions in order to create a target one. At each iteration, fixed costs and flows on arcs are transferred to nodes that are split consequently into categories. This information is used to update the target solution. With this approach the target solution represents the result of our learning, thus our proposed algorithm iterates by narrowing the search toward the target solution. When no more learning is observed, the target solution is dramatically modified by exploiting additional memory means (i.e. residency based memories) to reach new regions. An adaptive path relinking is then applied as a post-optimization technique to explore the solution space better.


15:10 A Branch-and-Cut Algorithm for Multicommodity Capacitated Fixed-Charge Network Problem
  Mervat Chouman, Université de Montréal, C.R.T. et Informatique et recherche opérationnelle, C.P. 6128, Succ. Centre-ville, Montréal, Québec, H3C 3J7
Teodor Gabriel Crainic, Université du Québec à Montréal, C.R.T., C.P. 6128, Succ. Centre-ville, Montréal, Québec, Canada, H3C 3J7
Bernard Gendron, Université de Montréal, C.R.T. et Informatique et recherche opérationnelle, C.P. 6128, Succ. Centre-ville, Montréal, Québec, Canada, H3C 3J7

The multicommodity capacitated fixed-charge network design problem (MCND) is a hard combinatorial optimization problem used to model a wide variety of applications in different areas such as transportation, telecommunication, production, etc. Recently, we have developed an efficient cutting-plane procedure which strengthens the usual LP relaxation. This procedure incorporates two families of cutset type inequalities, namely cover inequalities and minimum cardinality inequalities, in addition to new families of inequalities that we have developed for the single-node structure. In order to design an exact algorithm to solve the MCND, we propose a branch-and-cut algorithm (B&C) based on our cutting-plane procedure. In this talk we report on a branching rule, a fathoming rule and on a heuristic used to find a feasible solution. We also report computational results and compare them to those obtained by the B&C of the state-of-the-art CPLEX.


15:35 Variable Disaggregation in Network Flow Problems with Piecewise
  Bernard Gendron, Université de Montréal, C.R.T. et Informatique et recherche opérationnelle, C.P. 6128, Succ. Centre-ville, Montréal, Québec, Canada, H3C 3J7
Keely L. Croxton, The Ohio State University, Fisher College of Business, U.S.A.
Thomas L. Magnanti, Massachusetts Institute of Technology, School of Engineering and Sloan School of Management, U.S.A.

In this paper, we consider mixed-integer programming (MIP) formulations of a generic multi-commodity network flow problem with piecewise linear costs. The formulations we study are based on variable disaggregation techniques, which have been used for a while to derive strong MIP formulations for variants of the fixed-charge network flow problem, a special case of our generic problem.


16:00 Design de réseau manufacturier et de la planification des ressources pour une offre hautement personnalisée
  Marc Poulain, Université Laval, CENTOR, Québec, Québec, Canada, G1K 7P4
Benoit Montreuil, Université Laval, CENTOR, Québec, Québec, Canada, G1K 7P4
Alain Martel, Université Laval, CENTOR, Québec, Québec, Canada, G1K 7P4

La présentation porte sur le processus de design de réseau manufacturier et de la planification des ressources pour un manufacturier qui veut proposer une offre hautement personnalisée. Une méthode hybride constituée d’un heuristique et un modèle mathématique sera illustrée à travers d’un cas dans l’industrie du golf avec une emphase sur le niveau de service et les délais de livraison.