Séminaires : Séminaire Géométrie et Topologie

Ce séminaire s’adresse aux géomètres, topologues et dynamiciens au sens large. Il est rattaché aux équipes Analyse Algébrique et Analyse Complexe et Géométrie. Les exposés seront accessibles à une audience large, doctorants inclus. Il se tiendra à Jussieu, le jeudi à 11h, en salle 15-25 502. Le séminaire a l'agenda google suivante: https://calendar.google.com/calendar/b/0?cid=dDgzNTJoczNmdDhlMm5nb2IzMXJwaWpsdHNAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ

A point-pushing homeomorphism of a surface S is obtained (intuitively) by taking a point p on S and 'dragging' it along a closed loop based at p. The point-pushing subgroup of the pointed mapping class group MCG(S,p) consists of the isotopy classes of all such maps. It is known (due to a result of Broaddus, Farb and Putman) to be exponentially distorted; however, the precise word norm of a given point-pushing mapping class is not well-understood.

In this talk, we will discuss examples of distorted subgroups, including the point-pushing subgroup, as well as how we may attempt to predict the word-norm of a point-pushing mapping class by studying the loop which defines it.