Résumé : Given a group G, and a manifold M, can one describe all the ways that G acts on M ? This is a remarkably rich question even in the case where M is the line or the circle, and is connected to problems in dynamics, topology, and foliation theory.
This talk will describe one very useful way to capture such an action, namely, through the algebraic data of a left-invariant linear or circular order on a group. I’ll explain new work (joint with C. Rivas) that describes the space of orders on a group, and relates its topology to the moduli space of actions of G on the line or circle. As an application we’ll see new rigidity phenomena for actions, and the answers to some older algebraic questions about orderings.
Lieu : Bâtiment 425, salle 121-123
Notes de dernières minutes : Café culturel à 13h par Frédéric Paulin
Département de Mathématiques Bâtiment 425
Faculté des Sciences d'Orsay Université Paris-Sud
F-91405 Orsay Cedex
Tél. : +33 (0) 1-69-15-79-56