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.