Séminaire Algèbre Géométrie Algébrique Topologie Algébrique
jeudi 05 novembre 2009 à 11:15 - salle 431
Jon Berrick (National University of Singapore)
Delta-structure on braid and mapping class groups of surfaces
The starting-point for this work (joint with E Hanbury and J Wu) is the theorem that elements of homotopy groups of spheres may be represented by Brunnian braids on the 2-sphere. Brunnian braids are those that become trivial when any one strand is removed. We consider what information is contained in Brunnian braid groups and Brunnian mapping class groups on other surfaces.