English
Related papers

Related papers: Good objects in the equivariant world

200 papers

Let $G$ be an algebraic group and let $X$ be a smooth $G$-variety with two orbits: an open orbit and a a closed orbit of codimension $1$. We give an algebraic description of the category of $G$-equivariant vector bundles on $X$ under a mild…

Algebraic Geometry · Mathematics 2022-02-22 Lucas Mason-Brown , James Tao

We compute the homology of the space of equivariant loops on the classifying space of a simplicial monoid $M$ with anti-involution, provided $\pi_0 (M)$ is central in the homology ring of $M$. The proof is similar to McDuff and Segal's…

K-Theory and Homology · Mathematics 2020-11-11 Kristian Jonsson Moi

Using a homological invariant together with an obstruction class in a certain Ext^2-group, we may classify objects in triangulated categories that have projective resolutions of length two. This invariant gives strong classification results…

Operator Algebras · Mathematics 2017-04-20 Rasmus Bentmann , Ralf Meyer

We show that the bicategory of (representable) orbifolds and good maps is equivalent to the bicategory of orbifold translation groupoids and generalized equivariant maps. We use this result to define an orbifold version of Bredon…

Algebraic Topology · Mathematics 2010-03-10 Dorette Pronk , Laura Scull

In this paper, the categorial property of compactness of an object, i. e. commuting of the corresponding $\Hom$ functor with coproducts, is studied in categories of $S$-acts and the corresponding structural properties of compact $S$-acts…

Category Theory · Mathematics 2022-04-21 Josef Dvořák , Jan Žemlička

We prove that an action $\rho:A\to M(C_0(\mathbb{G})\otimes A)$ of a locally compact quantum group on a $C^*$-algebra has a universal equivariant compactification, and prove a number of other category-theoretic results on…

Operator Algebras · Mathematics 2022-04-28 Alexandru Chirvasitu

In this paper, we extend the notion of modular functor and fusion category to what we called $G$ equivariant modular functor and $G$ equivariant fusion category, where $G$ is a finite group, and establish a correspondence between between…

Quantum Algebra · Mathematics 2008-07-08 Alexander Kirillov , Tanvir Prince

The rational Borel equivariant cohomology for actions of a compact connected Lie group is determined by restriction of the action to a maximal torus. We show that a similar reduction holds for any compact Lie group $G$ when there is a…

Algebraic Topology · Mathematics 2024-02-14 Sergio Chaves

An action of a complex reductive group $\mathrm G$ on a smooth projective variety $X$ is regular when all regular unipotent elements in $\mathrm G$ act with finitely many fixed points. Then the complex $\mathrm G$-equivariant cohomology…

Algebraic Geometry · Mathematics 2026-05-27 Tamás Hausel , Kamil Rychlewicz

We develop the theory of nilpotent $G$-spaces and their localisations, for $G$ a compact Lie group, via reduction to the non-equivariant case using Bousfield localisation. One point of interest in the equivariant setting is that we can…

Algebraic Topology · Mathematics 2024-10-29 Andrew Ronan

We compute the $RO(C_p \times C_p)$-graded Bredon cohomology of equivariant universal and classifying spaces associated to families of subgroups, with coefficients in the constant Mackey functor $\underline{\mathbb{F}_p}$. An explicit…

Algebraic Topology · Mathematics 2026-03-12 Surojit Ghosh , Ankit Kumar

For a finite group $G$, we compute the algebraic $K$-theory of the category of equivariant sheaves on a locally compact Hausdorff $G$-space, generalizing a result of Efimov, and determine the equivariant $E$-theory of the $C^*$-algebra of…

K-Theory and Homology · Mathematics 2026-04-10 Guido Arnone , Devarshi Mukherjee , Thomas Nikolaus

Given a simple, simply connected compact Lie group G, let M be a G-space. We describe the quantization of the category of positive energy representations of the loop group of G at a given level and parametrized over the loop space LM. This…

Algebraic Topology · Mathematics 2018-05-17 Nitu Kitchloo

Starting categorically, we give simple and precise models of equivariant classifying spaces. We need these models for work in progress in equivariant infinite loop space theory and equivariant algebraic K-theory, but the models are of…

Algebraic Topology · Mathematics 2018-03-16 B. J. Guillou , J. P. May , M. Merling

We provide and study an equivariant theory of group (co)homology of a group G with coefficients in a gamma-equivariant G-module A, when a separate group "gamma" acts on G and A, generalizing the classical Eilenberg-MacLane (co)homology of…

K-Theory and Homology · Mathematics 2007-05-23 H. Inassaridze

We study stratification, that is the classification of localizing tensor ideal subcategories by geometric means, in the context of Kasparov's equivariant KK-theory of C*-algebras. We introduce a straightforward countable analog of the…

K-Theory and Homology · Mathematics 2026-01-21 Ivo Dell'Ambrogio , Rubén Martos

We study the classifying space of a twisted loop group $L_{\sigma}G$ where $G$ is a compact Lie group and $\sigma$ is an automorphism of $G$ of finite order modulo inner automorphisms. Equivalently, we study the $\sigma$-twisted adjoint…

Algebraic Topology · Mathematics 2016-03-09 Thomas Baird

We provide new $\infty$-categorical models for unstable and stable global homotopy theory. We use the notion of partially lax limits to formalize the idea that a global object is a collection of $G$-objects, one for each compact Lie group…

Algebraic Topology · Mathematics 2025-06-17 Sil Linskens , Denis Nardin , Luca Pol

Let G be a compact Lie group. Let M be a smooth G-manifold and V --> M be an oriented G-equivariant vector bundle. One defines the spaces of equivariant forms with generalized coefficients on V and M. An equivariant Thom form $\theta$ on V…

Differential Geometry · Mathematics 2007-05-23 Pascal Lavaud

We establish abstract Adams isomorphisms in an arbitrary equivariantly presentable equivariantly semiadditive global category. This encompasses the well-known Adams isomorphism in equivariant stable homotopy theory, and applies more…

Algebraic Topology · Mathematics 2024-10-03 Bastiaan Cnossen , Tobias Lenz , Sil Linskens