Infinite generation of non-cocompact lattices on right-angled buildings

Anne Thomas
University of Sydney, Sydney, Australia
11 May 2011, 2:30-3:30pm, Access Grid Room, University of Wollongong


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).

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