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J. P. C. Greenlees

Publications and source records attributed to J. P. C. Greenlees.

At least 37 records · Page 2Linked to original sources
arXiv2019

On the Balmer spectrum for compact Lie groups

We study the Balmer spectrum of the category of finite G-spectra for a compact Lie group G, extending the work for finite G by Strickland, Balmer-Sanders, Barthel-Hausmann-Naumann-Nikolaus-Noel-Stapleton and others. We give a description of the underlying set of the spectrum and show that the Balmer topology is completely determined by the inclusions between the prime ideals and the topology on the space of closed subgroups of G. Using this, we obtain a complete description of this topology for all abelian compact Lie groups and consequently a complete classification of thick tensor-ideals. For general compact Lie groups we obtain such a classification away from a finite set of primes p.

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arXiv2019

Adelic cohomology

The characteristic feature of the adeles is that they involve localizations of products (or equivalently restricted products of localizations). The point of this paper is to introduce an adelic style cohomological invariant of a partially ordered set with auxiliary structure which covers several examples of established interest in commutative algebra and stable equivariant homotopy theory.

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arXiv2019

An algebraic model for rational toral G-spectra

For G a compact Lie group, toral G-spectra are those rational G-spectra whose geometric isotropy consists of subgroups of a maximal torus of G. The homotopy category of rational toral G-spectra is a retract of the category of all rational G-spectra. In this paper we show that the abelian category defined by the second author in previous work gives an algebraic model for the toral part of rational G-spectra. This is a major step in establishing an algebraic model for all rational G-spectra, for any compact Lie group G.

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arXiv2018

An algebraic model for rational naive-commutative ring SO(2)-spectra and equivariant elliptic cohomology

Equipping a non-equivariant topological $E_\infty$-operad with the trivial $G$-action gives an operad in $G$-spaces. For a $G$-spectrum, being an algebra over this operad does not provide any multiplicative norm maps on homotopy groups. Algebras over this operad are called naïve-commutative ring $G$-spectra. In this paper we take $G=SO(2)$ and we show that commutative algebras in the algebraic model for rational $SO(2)$-spectra model rational naïve-commutative ring $SO(2)$-spectra. In particular, this applies to show that the $SO(2)$-equivariant cohomology associated to an elliptic curve $C$ from previous work of the second author is represented by an $E_\infty$-ring spectrum. Moreover, the category of modules over that $E_\infty$-ring spectrum is equivalent to the derived category of sheaves over the elliptic curve $C$ with the Zariski torsion point topology.

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arXiv2018

An algebraic model for rational torus-equivariant spectra

We show that the category of rational G-spectra for a torus G is Quillen equivalent to an explicit small and practical algebraic model, thereby providing a universal de Rham model for rational G-equivariant cohomology theories. The result builds on the first author's Adams spectral sequence, the second author's functors making rational spectra algebraic. There are several steps, some perhaps of wider interest (1) isotropy separation (replacing the category of G-spectra by modules over a diagram of isotropically simple ring G-spectra) (2) passage to fixed points on ring and module categories (replacing diagrams of ring G-spectra by diagrams of ring spectra) (3) replacing diagrams of ring spectra by diagrams of differential graded algebras (4) rigidity (replacing diagrams of DGAs by diagrams of graded rings). Systematic use of cellularization of model categories is central.

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arXiv2018

Couniversal spaces which are equivariant commutative ring spectra

The note identifies which which couniversal spaces have suspension spectra equivalent to commutative orthogonal ring G-spectra for a compact Lie group G. These are precisely those whose cofamily is closed under passage to finite index subgroups. Equivalently these are the couniversal spaces admitting an action of an equivariant E infinity operad.

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arXiv2017

Anderson and Gorenstein duality

The paper relates the Gorenstein duality statements studied by the first author to the Anderson duality statements studied by the second author, and explains how to use local cohomology and invariant theory to understand the numerology of shifts in simple cases.

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arXiv2017

Four approaches to cohomology theories with reality

We give an account of well known calculations of the RO(Q)-graded coefficient rings of some of the most basic Q-equivariant cohomology theories, where Q is a group of order 2. One purpose is to advertise the effectiveness of the Tate square, showing it has advantages over the slice spectral sequences in algebraically simple cases. A second purpose is to give a single account showing how to translate between the languages of different approaches. [v2 corrects some typos and adds some thanks and references, v3 corrects a few more typos].

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arXiv2017

An algebraic model for rational naive-commutative equivariant ring spectra

Equipping a non-equivariant topological E_\infty operad with the trivial G-action gives an operad in G-spaces. The algebra structure encoded by this operad in G-spectra is characterised homotopically by having no non-trivial multiplicative norms. Algebras over this operad are called naive-commutative ring G-spectra. In this paper we let G be a finite group and we show that commutative algebras in the algebraic model for rational G-spectra model the rational naive-commutative ring G-spectra.

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arXiv2017

The Balmer spectrum of rational equivariant cohomology theories

The category of rational G-equivariant cohomology theories for a compact Lie group $G$ is the homotopy category of rational G-spectra and therefore tensor-triangulated. We show that its Balmer spectrum is the set of conjugacy classes of closed subgroups of $G$, with the topology corresponding to the topological poset introduced in the author's study of rational Mackey functors. This is used to classify the collections of subgroups arising as the geometric isotropy of finite $G$-spectra. The ingredients for this classification are (i) the algebraic model of free spectra of the author and B.Shipley (arXiv 1101.4818), (ii) the Localization Theorem of Borel-Hsiang-Quillen and (iii) tom Dieck's calculation of the rational Burnside ring.

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arXiv2017

Gorenstein duality for Real spectra

Following Hu and Kriz, we study the $C_2$-spectra $BP\mathbb{R}\langle n \rangle$ and $E\mathbb{R}(n)$ that refine the usual truncated Brown-Peterson and the Johnson-Wilson spectra. In particular, we show that they satisfy Gorenstein duality with a representation grading shift and identify their Anderson duals. We also compute the associated local cohomology spectral sequence in the cases $n=1$ and $2$.

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arXiv2016

Rational torus-equivariant stable homotopy III: comparison of models

We give details of models for rational torus equivariant homotopy theory based on (a) all subgroups, connected subgroups or dimensions of subgroups and (b) on pairs or general flags. We provide comparison functors and show the models are equivalent. This is used in (A) An algebraic model for rational torus equivariant spectra (with B.Shipley; the new version of 1101.2511), (B) An algebraic model for the toral part of rational equivariant G-spectra for an arbitrary compact Lie group (1501.03425) and (C) construction of torus equivariant spectra from algebraic geometric data. It also highlights the role of the localization theorem in these models.

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arXiv2016

Homotopy Invariant Commutative Algebra over fields

These notes illustrates the power of formulating ideas of commutative algebra in a homotopy invariant form. They can then be applied to derived categories of rings or ring spectra. These ideas are powerful in classical algebra, in representation theory of groups, in classical algebraic topology and elsewhere. The notes grew out of a series of lectures given during the `Interactions between Representation Theory, Algebraic Topology and Commutative Algebra' (IRTATCA) at the CRM (Barcelona) in Spring 2015.

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arXiv2015

Rational SO(2)-Equivariant Spectra

We prove that the category of rational SO(2)-equivariant spectra has a simple algebraic model. Furthermore, all of our model categories and Quillen equivalences are monoidal, so we can use this classification to understand ring spectra and module spectra via the algebraic model.

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arXiv2015

Rational equivariant cohomology theories with toral support

For an arbitrary compact Lie group G, we describe a model for rational G-spectra with toral geometric isotropy and show that there is a convergent Adams spectral sequence based on it. The contribution from geometric isotropy at a subgroup K of the maximal torus of G is captured by a module over H^*(BW_G(K)_e) with an action of π_0(W_G(K)), where W_G(K)=N_G(K)/K and the subscript e denotes the identity component.

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arXiv2015

Ausoni-Bokstedt duality for topological Hochschild homology

We consider the Gorenstein condition for topological Hochschild homology, and show that it holds remarkably often. More precisely, if R is a commutative ring spectrum and and R----->k is a ring map to a field of characteristic p then, provided k is small as an R-module, THH(R;k) is Gorenstein in the sense of Dwyer-Greenlees-Iyengar. In particular, this holds if R is a (conventional) regular local ring with residue field k of characteristic p. Using only Bokstedt's calculation of THH(k), this gives a non-calculational proof of dualities observed in calculations by Bokstedt, McClure-Staffeldt, Ausoni-Rognes, Ausoni, Lindenstrauss-Madsen, Angeltweit-Rognes and others. A lemma of Dundas shows that THH(R;k) is remarkably computable.

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