A Geometric Proof of the Structure Theorem for Cyclic Splittings of Free Groups
arXiv:1208.3652
Abstract
We give a geometric proof of a well known theorem that describes splittings of a free group as an amalgamated product or HNN extension over the integers. The argument generalizes to give a similar description of splittings of a virtually free group over a virtually cyclic group.
11 pages, v2 added a reference