Mark Sapir
Vanderbilt University
Non-amenable groups without free subgroups, (joint with A. Olshanskii)
Abstract: We give a finitely presented counterexample to the von Neumann conjecture: a finitely presented non-amenable group without non-cyclic free subgroups. Our group is torsion-by-cyclic and satisfies the law [x,y]^n=1. This answers questions by Grigorchuk, Cohen, Gromov and others. Literature: The paper is just published in Publ. IHES (96, 2002). It is available on www.math.vanderbilt.edu/~msapir/publications.html and in the arXive. .