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A comparison of Takai and Treumann dualities

Vikram Nadig

Vol. 10 (2025), No. 3, 563–596
DOI: 10.2140/akt.2025.10.563
Abstract

We prove a comparison result between two duality statements — Takai duality, which is implemented by the crossed product functor G : KKG KKG^ on equivariant Kasparov categories, and Treumann duality, which asserts the existence of an exotic equivalence of stable -categories

Fun (BG,Perf (KUp)) Fun (BG^,Perf (KUp))

given by tensoring with a particular (G,G^)-bimodule M.

Keywords
$KK$-theory, Takai duality, Treumann duality
Mathematical Subject Classification
Primary: 19K35, 19L47
Secondary: 55P43
Milestones
Received: 24 October 2024
Revised: 12 August 2025
Accepted: 29 August 2025
Published: 6 October 2025
Authors
Vikram Nadig
Universität Bielefeld
Bielefeld
Germany