Abelian subalgebras of von Neumann algebras from flat tori in locally symmetric spaces

Autor: Guyan Robertson
Rok vydání: 2006
Předmět:
Zdroj: Journal of Functional Analysis. 230:419-431
ISSN: 0022-1236
DOI: 10.1016/j.jfa.2005.04.009
Popis: Consider a compact locally symmetric space M of rank r , with fundamental group Γ . The von Neumann algebra VN ( Γ ) is the convolution algebra of functions f ∈ l 2 ( Γ ) which act by left convolution on l 2 ( Γ ) . Let T r be a totally geodesic flat torus of dimension r in M and let Γ 0 ≅ Z r be the image of the fundamental group of T r in Γ . Then VN ( Γ 0 ) is a maximal abelian ★ -subalgebra of VN ( Γ ) and its unitary normalizer is as small as possible. If M has constant negative curvature then the Pukanszky invariant of VN ( Γ 0 ) is ∞ .
Databáze: OpenAIRE