Statut  Confirmé 
Série  MATHIHES 
Domaines  math 
Date  Mercredi 30 Janvier 2019 
Heure  14:30 
Institut  IHES 
Salle  Amphithéâtre Léon Motchane 
Nom de l'orateur  Bavard 
Prenom de l'orateur  Juliette 
Addresse email de l'orateur  
Institution de l'orateur  CNRS & Université de Rennes 1 
Titre  Two simultaneous actions of big mapping class groups 
Résumé  Mapping class groups of infinite type surfaces, also called "big" mapping class groups, arise naturally in several dynamical contexts, such as twodimensional dynamics, onedimensional complex dynamics, "Artinization" of Thompson groups, etc. In this talk, I will present recent objects and phenomena related to big mapping class groups. In particular, I will define two faithful actions of some big mapping class groups. The first is an action by isometries on a Gromovhyperbolic graph. The second is an action by homeomorphisms on a circle in which the vertices of the graph naturally embed. I will describe some properties of the objects involved, and give some fruitful relations between the dynamics of the two actions. For example, we will see that loxodromic elements (for the first action) necessarily have rational rotation number (for the second action). If time allows, I will explain how to use these simultaneous actions to construct nontrivial quasimorphisms on subgroups of big mapping class groups. This is joint work with Alden Walker. 
Numéro de preprint arXiv  
Commentaires  Séminaire Géométrie et groupes discrets 
Fichiers attachés 
Pour obtenir l' affiche de ce séminaire : [ Postscript  PDF ]

[ English version ] 