International Journal of Mathematics and Mathematical Sciences 
Volume 31 (2002), Issue 10, Pages 635-637
doi:10.1155/S0161171202013078

Powers of commutators as products of squares

M. Akhavan-Malayeri

Azzahra University, Vanak, Tehran 19834, Iran

Received 2 May 2001; Revised 13 January 2002

Abstract

Let F be a free group and x,y be two distinct elements of a free generating set, then [x,y]n is not a product of two squares in F, and it is the product of three squares. We give a short combinatorial proof.