Hyperbolicity of the complex of free factors (with Mladen Bestvina)

Mark Feighn, Rutgers

Abstract: A celebrated result of Masur-Minsky is the hyperbolicity of the curve complex, a naturally defined graph on which the mapping class group of a surface acts. We discuss joint work with Mladen Bestvina proving the analog for a naturally defined graph on which the outer automorphism group of a free group acts.