Montreal Geometric & Combinatorial Group Theory Seminar

Speaker: Daniel Wise (McGill)

Title: “*Counting W-cycles in Graphs, the Hanna
Neumann Conjecture, and the coherence of one-relator groups*”

Date: 3:30PM, Wednesday, October 15,
2003

Place: Room 920, Burnside Hall, McGill
University

Abstract:

I will discuss a conjecture about counting
certain cycles in a labelled directed graph. If the conjecture holds then every
one-relator group is "coherent" which means that all its finitely
generated subgroups are finitely presented. I will describe a connection with
the Hanna Neumann Conjecture, which plays a role in the proof. In particular, I
obtain the following result:

Theorem: < a, b, ... | W^n
> is coherent for
n>3, and for n>1 if the Hanna Neumann Conjecture holds.