Scl, rotation sets, and the fine curve graph

par Sebastian Hensel (University of Munich)

mardi 26 nov. 2024, 14:00 → 15:00 Europe/Paris

salle Fizeau (Valrose)

The fine curve graph is a Gromov hyperbolic graph on which the homeomorphism group of a surface acts, and which can be used to apply methods from geometric group theory and mapping class groups in order to study questions in surface dynamics. In previous work with Jonathan Bowden and Richard Webb we have shown that there are elements in the homeomorphism group of surfaces of genus at least 1 which have positive stable commutator length. In this talk I will present two new results which can certify that large classes of specific homeomorphisms have positive scl. One is joint with Bowden and Webb, and uses mapping class groups of surfaces, and the other is joint with Frédéric Le Roux and uses rotation sets.