Bulletin 105, Mai 99 

The seminar organized each year by the "3ème Cycle Romand de Recherche Opérationnelle" took place in the peaceful village of Zinal. The 36 participants coming from EPFs Lausanne and Zürich, the Universities of Fribourg and Genève, IDSIA (Lugano), and also from Italy and France attended this spring seminar. Three invited speakers have presented recent research results. These speakers were :

• Vasek Chvatal, Rutgers University, USA
  Combinatorial optimization
• Robert Fourer, Northwestern University, USA
  Design of modeling languages and systems for optimization
• Dean Carlson, Toledo University, USA
  Dynamic Games

Vasek Chvatal started with a very interesting history of the traveling salesman problem and depicted a TSP formulation as a linear objective combinatorial optimization problem. He presented then some results concerning heuristic tours and LP relaxation. Finally he focused the attention of the audience on the PQ-trees and how to use them efficiently.

Robert Fourer started with an history of programming, showing the evolution of systems and the links between modeler's form and algorithm's form. He then presented modeling language features for different fields (complementarity problems, combinational optimization, stochastic programming, constraint logic programming).

A third lecturer, Dean Carlson, first speaker of a preliminary session, has tried to convince the audience that dynamic games are efficient tools. Alain Haurie gave some useful additional information about this topic and introduced the notion of dynamic oligopoly.

We had the opportunity to get an insight into some of our students' and colleagues' research fields. The talks of about 20 minutes dealt with various subjects such as fair layout, vehicle routing problem, ACCPM algorithm, interior primal-dual method, LPL modeling language and design of waterpipe problem.

Despite a heavy program we were able to have fruitful discussions and make interesting contacts. The dinners were privileged moments of discussion in a relaxed atmosphere. A good scheduling allowed us to enjoy the sunny weather on the ski slopes which gave us a well appreciated break between the talks.

We would like to thank the organizer, Professor Alain Haurie (University of Genève), the invited speakers, the sponsor "3ème Cycle Romand de Recherche opérationnelle" as well as the ASRO/SVOR for their support.

Marino Widmer
marino.widmer@unifr.ch