English

Polygonic spectra and TR with coefficients

Algebraic Topology 2023-02-16 v1 K-Theory and Homology

Abstract

We introduce the notion of a polygonic spectrum which is designed to axiomatize the structure on topological Hochschild homology THH(R,M)\mathrm{THH}(R,M) of an E1\mathbb{E}_1-ring RR with coefficients in an RR-bimodule MM. For every polygonic spectrum XX, we define a spectrum TR(X)\mathrm{TR}(X) as the mapping spectrum from the polygonic version of the sphere spectrum S\mathbb{S} to XX. In particular if applied to X=THH(R,M)X = \mathrm{THH}(R,M) this gives a conceptual definition of TR(R,M)\mathrm{TR}(R,M). Every cyclotomic spectrum gives rise to a polygonic spectrum and we prove that TR agrees with the classical definition of TR in this case. We construct Frobenius and Verschiebung maps on TR(X)\mathrm{TR}(X) by exhibiting TR(X)\mathrm{TR}(X) as the Z\mathbb{Z}-fixedpoints of a quasifinitely genuine Z\mathbb{Z}-spectrum. The notion of quasifinitely genuine Z\mathbb{Z}-spectra is a new notion that we introduce and discuss inspired by a similar notion over Z\mathbb{Z} introduced by Kaledin. Besides the usual coherences for genuine spectra, this notion additionally encodes that TR(X)\mathrm{TR}(X) admits certain infinite sums of Verschiebung maps.

Keywords

Cite

@article{arxiv.2302.07686,
  title  = {Polygonic spectra and TR with coefficients},
  author = {Achim Krause and Jonas McCandless and Thomas Nikolaus},
  journal= {arXiv preprint arXiv:2302.07686},
  year   = {2023}
}

Comments

61 pages, comments are welcome

R2 v1 2026-06-28T08:40:46.838Z