Finitely Presented Groups Acting on Trees
arXiv:1203.6019
Abstract
It is shown that for any action of a finitely presented group on an -tree, there is a decomposition of as the fundamental group of a graph of groups related to this action. If the action of on is non-trivial, i.e. there is no global fixed point, then has a non-trivial action on a simplcial -tree.
18 pages, 8 figures. An incorrect example has been removed and the main result corrected