Elena Fernández (Technical University of Catalonia, Spain)
Short Biography
Elena Fernández obtained her Ph.D. in Computer Science at the Technical University of Catalonia (UPC) in 1988. Since 1989 she is Associate Professor in Statistics and Operations Research at UPC. In April 2005 she obtained the Spanish Habilitation for Full Professor.
She works in Integer Programming and Combinatorial Optimization, area in which she has supervised several doctoral theses. She has done several research stays in reputed international centers. Within the UPC she coordinates the research group “Mathematical Programming Logistics and Simulation”. She has participated and participates in several Spanish and European Research Projects. Since 2004 she coordinates the Spanish Location Network.
She is author or co-author of more than 25 scientific papers published in reputed journals of the area. She has also co-authored several book chapters and she has given over fifty presentations in international conferences. She has been a member of the Program Committee of several National and International Conferences, and she has co-organized several international events. She was Associate Editor of TOP in the period 1995-2000 and since 2003 she belongs to the Editorial Board of Computers and Operations research. In 1998 she was invited to join the IFIP working group 7.4 in Discrete Mathematics.
Lecture to be presented in EWI 2007
Title
Models
and algorithms for multistage location problems
Abstract
We
present different problems that allow addressing location decisions within a
time dependent context. In these problems the goal is to set a number of new
facilities over a finite time horizon so as to cover dynamically the demand of a
given set of costumers. In some cases we assume that customers receive service
only once throughout the planning horizon, whereas in other cases we assume that
once a customer starts being serviced, service is never interrupted until the
end of the planning horizon.
We analyze various modeling hypotheses that lead to models that can be suitable
in different situations, and we study the properties of the resulting models. In
particular, we can see that in the studied cases, the coefficient matrix of the
allocation subproblem that results when fixing the set of facilities to open is
totally unimodular. We also propose a model that is suitable for column
generation, where the prizing problem can be easily solved.
Finally, we illustrate a possible application of the proposed models within a
what-if scenario analysis for deciding the appropriate number of time instants
where the location decisions should be made, for achieving a trade-off between
the service level and operation cost.