Mardi 12 Mars

Heure:	12:30 - 13:30
Lieu:	Salle B107, bâtiment B, Université de Villetaneuse
Résumé:	Reverse Chvatal-Gomory rank.
Description:	Roland Grappe We introduce the reverse Chvatal-Gomory rank r*(P) of an integral polyhedron P, defined as the supremum of the Chvatal-Gomory ranks of all rational polyhedra whose integer hull is P. A well-known example in dimension two shows that there exist integral polytopes P with r*(P) infinite. We provide a geometric characterization of polyhedra with this property in general dimension, and investigate upper bounds on r*(P) when this value is finite. This is a joint work with Michele Conforti, Alberto Del Pia, Marco Di Summa and Yuri Faenza. 

Heure:	14:00 - 17:00
Lieu:	Salle B107, bâtiment B, Université de Villetaneuse
Résumé:	Bipartite subfamilies of planar graphs
Description:	Juanjo Rué Perna I will survey the techniques used to get asymptotic results for subfamilies of planar graphs, as well as how to relate this methodology with the context of map enumeration. In the second part of the talk, I willexplain the ideas behind some on-going projects related to the enumeration of bipartite subfamilies of graphs.