2001/07/10 by Allan M. Sinclair, Allan Sinclair, Roger Smith +3
Mathematics · #Advanced Operator Algebra Research #Geometric and Algebraic Topology #Spectral Theory in Mathematical Physics #math.OA #msc:46L05
paper · pdf · doi:10.48550/arxiv.math/0107076
16 pages, latex file
arxiv created 2001/07/10 · arxiv updated 2009/11/30
The Laplacian (or radial) masa in a free group factor is generated by the sum of the generators and their inverses. We show that such a masa B is strongly singular and has Popa invariant delta(B) = 1. This is achieved by proving that the conditional expectation onto B is an asymptotic homomorphism. We also obtain similar results for the free product of discrete groups, each of which contains an element of infinite order.