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20222026
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math.OA2026

Selfless nonnuclear crossed products

Jamie Bell

For a strictly ergodic action of a countable discrete group with Ozawa's property PHP on the Cantor set, we prove that dynamical comparison implies complete selflessness of its red…

math.OA2026

Factorisation and matrix amplification of real rank zero inclusions

Jamie Bell

We show that real rank zero is not preserved under matrix amplifications of inclusions. This yields real rank zero inclusions that do not approximately factor through real rank zer…

math.OA2026

Nonamenable groups whose reduced group C*-algebras are not pure

Jamie Bell

We exhibit nonamenable groups whose reduced group C*-algebras are not pure. More precisely, if is any countably infinite discrete group, then the reduced group C*-algebra of th…

math.OA2026

Nonnuclear Bunce-Deddens algebras

Jamie Bell

We introduce nonnuclear Bunce-Deddens algebras, defined as reduced crossed product C*-algebras associated with free odometer actions of nonamenable countable discrete residually fi…

math.OA2026

Crossed product C*-algebras associated with non-minimal actions on the circle

Jamie Bell

We examine crossed product C*-algebras associated with free non-minimal actions of countably infinite discrete abelian groups on the circle, extending the work of Putnam, Schmidt,…

math.OA2025

Stable rank one in nonnuclear crossed products

Jamie Bell, Shirly Geffen, David Kerr

We initiate an investigation into the local structure of simple nonnuclear C-crossed products by showing that stable rank one is generic within two natural classes of minimal a…