UPDATE: the order of speakers has been inverted, and both talks will be in Carslaw 175 (not the AGR). The next Group Actions Seminar will be on Wednesday 20 June at the University of Sydney. The speakers are Stephan Tillmann (Sydney) at 12 noon and Joseph Maher (CUNY Staten Island) at 3pm. Their titles and abstracts are below. ---------------------------------------------------------------------------- Date: Wednesday 20 June Time: 12 noon Location: Carslaw 175, University of Sydney Speaker: Stephan Tillmann (Sydney) Title: Finite volume projective manifolds Abstract: A convex real projective manifold or orbifold is M/G, where M is the interior of a compact convex set in real projective space disjoint from some hyperplane and G is a discrete group of projective transformations which preserves M. The manifold is strictly convex if there is no line segment in the boundary of M. Strictly convex structures have many similarities to hyperbolic structures, particularly in the finite volume case. By contrast, properly convex structures are far more general. I will discuss aspects of projective manifolds from the perspective of a low-dimensional topologist, giving a snap-shot of the material in the paper arXiv:1109.0585 with Cooper and Long. ---------------------------------------------------------------- Date: Wednesday 20 June Time: 3pm Location: Carslaw 175, University of Sydney Speaker: Joseph Maher (CUNY Staten Island) Title: Growth rates for stable commutator length Abstract: We give a gentle introduction to stable commutator length, and then show that stable commutator length grows as n / log n, where n is the length of a random walk or random geodesic in a hyperbolic group. ----------------------------------------------------------------