Type: Seminar

Distribution: World

Expiry: 11 May 2011

Auth: athomas@p615.pc (assumed)

The next Infinite Groups Seminar will be this Wednesday 11 May at the University of Wollongong. The schedule, titles and abstracts are below. The first talk by Jacqui Ramagge will be broadcast over the Access Grid. If you would like to watch this talk at Sydney please contact Robert Pearson. -------------------------------------------------------------------------- 12:30pm, Access Grid Room, University of Wollongong Speaker: Jacqui Ramagge Title: Infinite groups, geometries and operator algebras Abstract: Examples are of critical importance in operators algebras; the lack of decomposition theorems means we can’t use the standard trick of breaking objects down into simple pieces, studying the pieces and inferring information about the whole. Infinite groups acting on geometries enable us to generate a surprisingly large class of examples of operator algebras. While the impact of the work is in the field of operator algebras, I will focus on the groups and the geometries, which is where the action is (pun not originally intended but irresistible once noted). 2:30pm, room TBA Speaker: Anne Thomas Title: Infinite generation of non-cocompact lattices on right-angled buildings Abstract: Let Gamma be a non-cocompact lattice on a right-angled building X. Examples of such X include products of trees, or Bourdon’s building I_{p,q}, which has apartments hyperbolic planes tesselated by right-angled p-gons and all vertex links the complete bipartite graph K_{q,q}. We prove that if Gamma has a strict fundamental domain then Gamma is not finitely generated. The proof uses a topological criterion for finite generation and the separation properties of subcomplexes of X called tree-walls. This is joint work with Kevin Wortman (Utah). -------------------------------------------------------------------------