Paper published by Algebraic and Geometric Topology

From: Geometry and Topology Journal (gt_at_maths.warwick.ac.uk)
Date: 08/16/04 

Date: 16 Aug 2004 13:15:01 -0400

A paper has been published and also a provisional erratum for a
previously published paper (see end). 

---
The following paper has been published. 
Algebraic and Geometric Topology
Volume 4 (2004), paper no. 27, pages 595--602
URL:
http://www.maths.warwick.ac.uk/agt/AGTVol4/agt-4-27.abs.html
Title:
Commutators and squares in free groups
Author(s):
Sucharit Sarkar
Abstract:
Let F_2 be the free group generated by x and y. In this article, we
prove that the commutator of x^m and y^n is a product of two squares
if and only if mn is even. We also show using topological methods that
there are infinitely many obstructions for an element in F_2 to be a
product of two squares.
AMS Classification Numbers. Primary: 20F12
Secondary: 57M07
Keywords:
Commutators, free groups, products of commutators
Received: 2 January 2003
Revised: 25 March 2004
Accepted: 12 July 2004
Published: 5 November 2003
Author(s) address(es):
Stat-Math Unit, Indian Statistical Institute 
Bangalore, India
Email: bmat0212@isibang.ac.in
---
An error has been found in the following paper.  A full erratum will
be published in due course.  In the meanwhile a provisional erratum is
available (linked from the URL below).
"K-theory of virtually poly-surface groups"  by  S.K. Roushon
Algebraic and Geometric Topology 3 (2003) 103-116 
URL: 
http://www.maths.warwick.ac.uk/agt/AGTVol3/agt-3-4.abs.html