The subgroup stratification of Nakaoka spectra

Fuente: arXiv
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Main Author: Wisdom, Noah
Format: Preprint
Published: 2025
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author Wisdom, Noah
author_facet Wisdom, Noah
contents We construct a stratification on the Nakaoka spectrum of any $G$-Tambara functor indexed by the poset of subgroups of $G$. When $G$ is Dedekind, we show that the $H$th stratum of the Nakaoka spectrum of the Burnside $G$-Tambara functor is closed and not open; this provides examples of étale maps which induce closed, non-open maps on Nakaoka spectra. By computing the strata on the ghost of a $C_p$-Tambara functor we obtain many examples of étale maps of Tambara functors for which the induced map on Nakaoka spectra is not open, in contrast to the non-equivariant world. We also compute the strata of all fixed-point Tambara functors.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09360
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The subgroup stratification of Nakaoka spectra
Wisdom, Noah
Algebraic Topology
Algebraic Geometry
We construct a stratification on the Nakaoka spectrum of any $G$-Tambara functor indexed by the poset of subgroups of $G$. When $G$ is Dedekind, we show that the $H$th stratum of the Nakaoka spectrum of the Burnside $G$-Tambara functor is closed and not open; this provides examples of étale maps which induce closed, non-open maps on Nakaoka spectra. By computing the strata on the ghost of a $C_p$-Tambara functor we obtain many examples of étale maps of Tambara functors for which the induced map on Nakaoka spectra is not open, in contrast to the non-equivariant world. We also compute the strata of all fixed-point Tambara functors.
title The subgroup stratification of Nakaoka spectra
topic Algebraic Topology
Algebraic Geometry
url https://arxiv.org/abs/2508.09360