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Vol. 2, Issue 1

Algebraic KK-Theory and Trace Methods

Henrik Bjørnsen (University of Copenhagen)

Algebraic KK-theory captures deep arithmetic and geometric information about rings, but direct computation of Kn(A)K_n(A) for n2n \geq 2 is notoriously difficult. The cyclotomic trace trc:K(A)TC(A)\text{trc}: K(A) \to \text{TC}(A) to topological cyclic homology provides a powerful computational tool. Following the Nikolaus-Scholze framework, we define TC(A)\text{TC}(A) via the equalizer of Frobenius and canonical maps on THH(A)tCp\text{THH}(A)^{tC_p}, and demonstrate how this leads to explicit calculations of KK-groups for pp-adic integers and truncated polynomial algebras.

Subject areas:

Date Filmed: January 14, 2026

Location Filmed: University of Copenhagen

MSC Codes: 19D55, 19F27

Funding information: NSF grant DMS-2310203

A modern account of algebraic KK-theory computations via the cyclotomic trace to topological cyclic homology.

Cite this talk

Henrik Bjørnsen. "Algebraic K-Theory and Trace Methods". In: Mathematical Discourse 2.1 (2026). URL: https://mathematical-discourse-sable.vercel.app/issue/vol-2-issue-1/algebraic-k-theory-trace-methods.