[Binghamton Geometry/Topology Seminar] (no subject)

[Marco Varisco]

BINGHAMTON GEOMETRY/TOPOLOGY SEMINAR
  http://www.math.binghamton.edu/dept/topsem/

Date: Thursday, February 14, 2008

Time: 2:50 pm

Place: Library North 2205
  (followed by coffee/tea in the Anderson Reading Room)

Speaker: Jose Burillo (Universitat Politecnica de Catalunya)

Title: Commensurators and finite-index subgroups of Thompson's group F

Abstract: In this talk we will give a complete description of the
abstract commensurator of Thompson's group F, and we will prove that
it embeds in the quasi-isometry group of F, hence providing a large
number of examples of quasi-isometries of F.  As a corollary of this
result, we classify all finite-index subgroups of F, proving that they
are all virtually F, and identifying exactly those which are
isomorphic to F itself.  (Joint work with Sean Cleary and Claas
Roever.)