Forester's lattices and small non-Leighton complexes

Abstract

We construct two CW-complexes $K$ and $L$ admitting a common, but not finite common, covering, where $K$ is homeomorphic to a complex with a single 2-cell.

6 pages. A Russian version of this paper is at http://halgebra.math.msu.su/staff/klyachko/papers.htm . V3: details are added, an error and misprints are corrected --- thanks to an anonymous referee