Title: Nonpositive Immersions, the Strengthened Hannah Neumann Conjecture, and the coherence of one-relator groups with torsion

Dani Wise  (McGill)

Friday, September 26 at 1:15pm in Mathematics 507.

Abstract:

A group G is "locally indicable" if every nontrivial finitely generated subgroup of G has an infinite cyclic quotient. A group G is "coherent" if every finitely generated subgroup of G is finitely presentable. In the first part of my talk I will discuss the "nonpositive immersion" hypothesis which is a curious Euler characteristic condition on a 2-complex X that implies that the fundamental group of X is both locally indicable and coherent. In the second part of my talk I will apply this towards the coherence of one-relator groups with torsion, using Walter Neumann's Strengthened Hanna Neumann Conjecture.