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
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.