English

The Laplacian Masa in a Free Group Factor

Operator Algebras 2007-05-23 v1

Abstract

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.

Keywords

Cite

@article{arxiv.math/0107076,
  title  = {The Laplacian Masa in a Free Group Factor},
  author = {Allan Sinclair and Roger Smith},
  journal= {arXiv preprint arXiv:math/0107076},
  year   = {2007}
}

Comments

16 pages, latex file

R2 v1 2026-07-22T16:39:33.770Z