[Binghamton Geometry/Topology Seminar] February 19

[Marco Varisco]

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

Date:  Thursday, February 19, 2009

Time:  2:50 pm

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

Speaker:  Adam Piggott (Bucknell University)

Title:  The automorphism group of the free group of rank two is a CAT(0) group

Abstract:  We discuss a recent project with Kim Ruane and Genevieve
Walsh, in which we prove that the automorphism group of the braid
group on four strands acts faithfully and geometrically on a CAT(0)
2-complex. This implies that the automorphism group of the free group
of rank two acts faithfully and geometrically on a CAT(0) 2-complex,
in contrast to the situation for rank three and above.