English

G-typical Witt vectors with coefficients and the norm

Algebraic Topology 2025-09-16 v2 Commutative Algebra K-Theory and Homology

Abstract

For a profinite group GG we describe an abelian group WG(R;M)W_G(R; M) of GG-typical Witt vectors with coefficients in an RR-module MM (where RR is a commutative ring). This simultaneously generalises the ring WG(R)W_G(R) of Dress and Siebeneicher and the Witt vectors with coefficients W(R;M)W(R; M) of Dotto, Krause, Nikolaus and Patchkoria, both of which extend the usual Witt vectors of a ring. We use this new variant of Witt vectors to give a purely algebraic description of the zeroth equivariant stable homotopy groups of the Hill-Hopkins-Ravenel norm N{e}G(X)N_{\{e\}}^G(X) of a connective spectrum XX, for any finite group GG. Our construction is reasonably analogous to the constructions of previous variants of Witt vectors, and as such is amenable to fairly explicit concrete computations.

Keywords

Cite

@article{arxiv.2305.20064,
  title  = {G-typical Witt vectors with coefficients and the norm},
  author = {Thomas Read},
  journal= {arXiv preprint arXiv:2305.20064},
  year   = {2025}
}

Comments

Accepted for publication by the Journal of Topology, minor corrections and improved explanations compared to the original preprint. 85 pages

R2 v1 2026-06-28T10:52:19.990Z