Optimal regularity of mapping class group actions on the circle

Abstract: We prove that for each finite index subgroup $H$ of the mapping class group of a closed hyperbolic surface, and for each real number $r>0$ there does not exist a faithful $C^{1+r}$--action of $H$ on a circle. (Joint with Thomas Koberda and Cristobal Rivas)

group theory

Audience: researchers in the discipline

Symmetry in Newcastle