Speaker: Lars Louder (Warwick)

Title: Strong accessibility for finitely presented groups

Abstract: A hierarchy for a group $G$ is a tree of groups obtained by iteratively passing to vertex groups of graphs of groups decompositions of subgroups of $G$, a la the Haken hierarchy for a Haken three-manifold. I will explain why certain kinds of hierarchies of finitely presented groups must be finite, and the role they play in the proof that varieties defined over free groups must have finite Krull dimension.