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Related papers: Clarification and Coinduction of Tambara Functors

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Tambara functors arise in equivariant homotopy theory as the structure adherent to the homotopy groups of a coherently commutative equivariant ring spectrum. We show that if $k$ is a field-like $C_{p^n}$-Tambara functor, then $k$ is the…

Algebraic Topology · Mathematics 2025-03-07 Noah Wisdom

We survey and extend the theory of Tambara functors. These are algebraic structures similar to Mackey functors, but with multiplicative norm maps as well as additive transfer maps, and a rule governing their interaction that is most easily…

Algebraic Topology · Mathematics 2012-05-14 Neil Strickland

Tambara functors are an equivariant generalization of rings that appear as the homotopy groups of genuine equivariant commutative ring spectra. In recent work, Blumberg and Hill have studied the corresponding algebraic structures, called…

Algebraic Topology · Mathematics 2024-01-31 David Chan

For a "genuine" equivariant commutative ring spectrum $R$, $\pi_0(R)$ admits a rich algebraic structure known as a Tambara functor. This algebraic structure mirrors the structure on $R$ arising from the existence of multiplicative norm…

Algebraic Topology · Mathematics 2018-03-16 Andrew J. Blumberg , Michael A. Hill

Bi-incomplete Tambara functors are equivariant generalizations of commutative rings. The most common forms of bi-incomplete Tambara functors are coefficient systems of commutative rings, Green functors, and Tambara functors. In the 1980s,…

Algebraic Topology · Mathematics 2026-05-11 Scott Balchin , J. D. Quigley , Ben Spitz

It is well known that the zeroth stable homotopy group of a genuine equivariant commutative ring spectrum has multiplicative transfers (norms), making it into a Tambara functor. We prove here that all Tambara functors can be obtained in…

Algebraic Topology · Mathematics 2013-05-23 John Ullman

We lift to equivariant algebra three closely related classical algebraic concepts: abelian group objects in augmented commutative algebras, derivations, and K\"ahler differentials. We define Mackey functor objects in the category of Tambara…

Algebraic Topology · Mathematics 2017-01-24 Michael A. Hill

In this paper we extend equivariant infinite loop space theory to take into account multiplicative norms: For every finite group $G$, we construct a multiplicative refinement of the comparison between the $\infty$-categories of connective…

Algebraic Topology · Mathematics 2024-07-12 Bastiaan Cnossen , Rune Haugseng , Tobias Lenz , Sil Linskens

For a finite group $G$, a semi-Mackey (resp. Tambara) functor is regarded as a $G$-bivariant analog of a commutative monoid (resp. ring). As such, some naive algebraic constructions are generalized to this $G$-bivariant setting. In this…

Category Theory · Mathematics 2011-03-22 Hiroyuki Nakaoka

For a finite group $G$, a Tambara functor on $G$ is regarded as a $G$-bivariant analog of a commutative ring. In this article, we consider a $G$-bivariant analog of the ideal theory for Tambara functors.

Category Theory · Mathematics 2011-03-22 Hiroyuki Nakaoka

Derived equivalences and t-structures are closely related. We use realisation functors associated to t-structures in triangulated categories to establish a derived Morita theory for abelian categories with a projective generator or an…

Representation Theory · Mathematics 2017-07-26 Chrysostomos Psaroudakis , Jorge Vitória

Tambara functors are the analogue of commutative rings in equivariant algebra. Nakaoka defined ideals in Tambara functors, leading to the definition of the Nakaoka spectrum of prime ideals in a Tambara functor. In this work, we continue the…

Algebraic Topology · Mathematics 2026-03-13 David Chan , David Mehrle , J. D. Quigley , Ben Spitz , Danika Van Niel

In this note we consider different versions of coinduction functors between categories of comodules for corings induced by a morphism of corings. In particular we introduce a new version of the coinduction functor in the case of locally…

Rings and Algebras · Mathematics 2007-05-23 Jawad Abuhlail

For all subgroups $H$ of a cyclic $p$-group $G$ we define norm functors that build a $G$-Mackey functor from an $H$-Mackey functor. We give an explicit construction of these functors in terms of generators and relations based solely on the…

Algebraic Topology · Mathematics 2019-08-02 Michael A. Hill , Kristen Mazur

In this paper we give detailed algebraic descriptions of the derived symmetric power and norm constructions on categories of Mackey functors, as well as the derived G-symmetric monoidal structure. We build on the results of [Ull2], in which…

Algebraic Topology · Mathematics 2013-05-23 John Ullman

For an equivariant commutative ring spectrum $R$, $\pi_0 R$ has algebraic structure reflecting the presence of both additive transfers and multiplicative norms. The additive structure gives rise to a Mackey functor and the multiplicative…

Algebraic Topology · Mathematics 2021-04-22 Andrew J. Blumberg , Michael A. Hill

Let $G$ be a finite group, and $k$ an integer. In this note, we show that for any $G$-Tambara functor $T$ and any subgroups $H_1, H_2 \leq G$, $k$ is a unit in $T(G/H_1)$ if and only if $k$ is a unit in $T(G/H_2)$. In other words, one may…

Group Theory · Mathematics 2026-01-27 Ben Spitz

Consider a coring with exact rational functor, and a finitely generated and projective right comodule. We construct a functor (\emph{coinduction functor}) which is right adjoint to the hom-functor represented by this comodule. Using the…

Rings and Algebras · Mathematics 2009-02-13 L. El Kaoutit , J. Gómez-Torrecillas

For a finite group $G$, (semi-)Mackey functors and (semi-)Tambara functors are regarded as $G$-bivariant analogs of (semi-)groups and (semi-)rings respectively. In fact if $G$ is trivial, they agree with the ordinary (semi-)groups and…

Category Theory · Mathematics 2011-05-25 Hiroyuki Nakaoka

We give a characterisation of functors whose induced functor on the level of localisations is an equivalence and where the isomorphism inverse is induced by some kind of replacements such as projective resolutions or cofibrant replacements.

Category Theory · Mathematics 2018-10-11 Sebastian Thomas
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