University of Chicago
Abstract: Surfaces are one of the fundamental objects in mathematics; they lie at the intersection of geometry, topology, complex analysis and group theory. Even better than surfaces are minimal surfaces --- those which are the simplest, or the smallest, for the job they have to do. I will talk about what "minimal" means in topology and group theory, and how solving a topological minimization problem can give rise to geometry.
A finitely presented group of piecewise
Abstract: I will describe a finitely presented subgroup of Monod¢s group of piecewise projective homeomorphisms of the real line. This in particular provides a new example of a finitely presented group which is nonamenable and yet does not contain a nonabelian free subgroup. Our example is moreover torsion free. This is joint work with Yash Lodha.