> Department of Management Science
> Seminar
>
> At 2.30 pm on Friday 2nd May 2003
> in Lecture Theatre C103 Graduate School, Lancaster University
>
> Laurence A. Wolsey
> CORE, Universite Catholique de Louvain
>
>
> Solving Multi-Item Lot-Sizing Problems using
> Classification and Automatic Reformulation
>
>
> Abstract
>
>
> Based on research on the polyhedral structure of lot-sizing models over the
> last twenty years, there is a nontrivial fraction of practical lot-sizing
> problems that can now be solved by taking an appropriate a priori
> reformulation of the problem, and then feeding the resulting formulation into
> a commercial mixed integer programming solver. This approach is based on the
> fact that many multi-item problems decompose naturally into a set of
> single-item problems with linking constraints, and that there is now a large
> body of knowledge about single-item problems. To put this knowledge to use,
> we have proposed a classification of lot-sizing problems (in large part
> single-item), and then it is easy to see via a set of Tables what is known
> about a particular problem class, and how useful it might be. The
> nonspecialist user is asked to provide an initial mixed integer programming
> formulation of his problem in a modelling language such as Mosel or AMPL, and
> an appropriate classification of his problem. Then it su±ces to copy the
> correct reformulation from a library of models, and run the problem. For
> users of Mosel, we have developed a simple interface XFORMLIB to automate
> this approach (as part of the EU project LISCOS). Several multi-item
> lot-sizing instances are then presented to demonstrate the approach, and
> comparative computational results are presented.
>
|