Group Actions Seminar: Tillmann, Maher

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.  

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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.  

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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.  

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