I have renamed the Infinite Groups Seminar to the Group Actions Seminar. Our first meeting for 2012 will be held at the University of Sydney on Monday 20 February, with Derek Holt and Anne Thomas speaking. Details are below. ---------------------------------------------------------------------------- Date: Monday 20 February Time: 12 noon Location: Room 830, Carslaw Building, University of Sydney Speaker: Derek Holt (University of Warwick) Title: Automaticity of Artin groups Abstract: After a brief resumee of the definition and basic properties of automatic groups, we discuss the question of which Artin groups are automatic. This has been proved for various types of Artin groups by Charney, Hermiller and Meier, Peiffer, Brady and McCammond, and others. We report on recent work with Sarah Rees that certain other types of Artin groups, including all of those of large-type, are automatic. ---------------------------------------------------------------- Date: Monday 20 February Time: 2:30pm Location: Room 829 (Access Grid Room), Carslaw Building, University of Sydney Speaker: Anne Thomas (University of Sydney) Title: Divergence in right-angled Coxeter groups Abstract: The divergence of a pair of geodesics emanating from a point in a metric space is a measure of how quickly they are moving away from each other. In Euclidean space divergence is linear, while in hyperbolic space divergence is exponential. Gersten used this idea to define a quasi-isometry invariant for groups, which has been investigated for classes of groups including 3-manifold groups, mapping class groups and right-angled Artin groups. I will discuss joint work with Pallavi Dani on divergence in the class of right-angled Coxeter groups. ----------------------------------------------------------------