Algebraic & Geometric Topology 9 (2009) 327–335

DOI: 10.2140/agt.2009.9.327

Abstract

We construct an efficient model for graphs of finitely generated subgroups of free groups. Using this we give a very short proof of Dicks’s reformulation of the strengthened Hanna Neumann Conjecture as the Amalgamated Graph Conjecture. In addition, we answer a question of Culler and Shalen on ranks of intersections in free groups. The latter has also been done independently by R P Kent IV.

Keywords

folding, free groups, Hanna Neumann conjecture

Mathematical Subject Classification

Primary: 20E05

References

Publication

Received: 27 August 2008
Revised: 25 January 2009
Accepted: 28 January 2009
Published: 23 February 2009

Authors