Mardi 3 Décembre
Heure: 
12:00  13:30 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
A branchandbound method for box constrained integer polynomial optimization 
Description: 
Claudia D'Ambrosio We consider the problem of minimizing an arbitrary polynomial subject to box and integrality constraints. We propose a new class of underestimators composed of separable functions of the original variables and use it within a branchandbound scheme to easily and quickly compute lower bounds. Computational results on randomly generated instances show good performance with respect to the ones of different opensource solvers like Couenne, Gloptipoly , and SCIP. Moreover, the second part of the talk will be devoted to present a different perspective on partially separable problems. In particula, an exact algorithm for mixed integer nonlinear programming problems with separable nonconvexities will be presented. 
Mardi 17 Décembre
Heure: 
12:00  13:30 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Konig's edgecolouring theorem for all graphs 
Description: 
Denis Cornaz We show that the maximum degree of a graph G is equal to the minimum number of ocm sets covering G, where an ocm set is the vertexdisjoint union of elementary odd cycles and one matching, and a collection of ocm sets covers G if every edge is in the matching of an ocm set or in some odd cycle of at least two ocm sets. This minmax relation gives a linear description of the star polytope with a minimal TDIsystem. Joint work with V. H. Nguyen from LIP6. 

