Extensions of the reduced group C*-algebra of a free product of amenable groups

2009/02/19 by Jonas Andersen Seebach, Klaus Thomsen, Seebach, Jonas Andersen +1
Mathematics · #46L80 #Advanced Banach Space Theory #Advanced Operator Algebra Research #Advanced Topics in Algebra #FOS: Mathematics #Operator Algebras (math.OA)

paper · pdf · doi:10.48550/arxiv.0902.3375

openalex publication_date 2009/02/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We prove that the unitary equivalence classes of extensions of C*_r(G) by any sigma-unital stable C"-algebra, taken modulo extensions which split via an asymptotic homomorphism, form a group which can be calculated from the universal coefficient theorem of KK-theory when G is a free product of a countable collection of amenable groups.

Related

• Extensions of C*-algebras
• Amenability for unitary groups of simple monotracial C*-algebras
• Amenability for unitary groups of C*-algebras
• Asymptotic representations of the reduced C*-algebra of a free group: an example
• Perturbations of crossed product C*-algebras by amenable groups