Separable commutative algebras in equivariant homotopy theory

Fuente: arXiv
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Hauptverfasser: Naumann, Niko, Pol, Luca, Ramzi, Maxime
Format: Preprint
Veröffentlicht: 2024
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author Naumann, Niko
Pol, Luca
Ramzi, Maxime
author_facet Naumann, Niko
Pol, Luca
Ramzi, Maxime
contents Given a finite group $G$ and a commutative ring $G$-spectrum $R$, we study the separable commutative algebras in the category of compact $R$-modules. We isolate three conditions on the geometric fixed points of $R$ which ensure that every separable commutative algebra is standard, i.e. arises from a finite $G$-set. In particular we show that all separable commutative algebras in the categories of compact objects in $G$-spectra and in derived $G$-Mackey functors are standard provided that $G$ is a $p$-group. In these categories we also show that for a general finite group $G$, not all separable commutative algebras are standard. We finally discuss how the classification of separable commutative algebras in compact $G$-spectra varies if we require the existence of multiplicative norms. We show that if $G$ is solvable, then any separable commutative algebra therein that is normed is automatically standard. However, if $G$ is not solvable, we provide examples of separable commutative algebras that are normed but not standard.
format Preprint
id arxiv_https___arxiv_org_abs_2411_06845
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Separable commutative algebras in equivariant homotopy theory
Naumann, Niko
Pol, Luca
Ramzi, Maxime
Algebraic Topology
Given a finite group $G$ and a commutative ring $G$-spectrum $R$, we study the separable commutative algebras in the category of compact $R$-modules. We isolate three conditions on the geometric fixed points of $R$ which ensure that every separable commutative algebra is standard, i.e. arises from a finite $G$-set. In particular we show that all separable commutative algebras in the categories of compact objects in $G$-spectra and in derived $G$-Mackey functors are standard provided that $G$ is a $p$-group. In these categories we also show that for a general finite group $G$, not all separable commutative algebras are standard. We finally discuss how the classification of separable commutative algebras in compact $G$-spectra varies if we require the existence of multiplicative norms. We show that if $G$ is solvable, then any separable commutative algebra therein that is normed is automatically standard. However, if $G$ is not solvable, we provide examples of separable commutative algebras that are normed but not standard.
title Separable commutative algebras in equivariant homotopy theory
topic Algebraic Topology
url https://arxiv.org/abs/2411.06845