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The group of continuous binary operations on a topological space is studied; its relationship with the group of homeomorphisms is established. The category of binary $G$-spaces and bi-equivariant maps is constructed, which is a natural…

General Topology · Mathematics 2023-07-13 Pavel S. Gevorgyan

Let G be a connected reductive group. Recall that a G-variety X is called spherical if X is normal and a Borel subgroup of G has an open orbit on X. To a spherical homogeneous G-space one assigns certain combinatorial invariants: the weight…

Algebraic Geometry · Mathematics 2009-05-30 Ivan V. Losev

Equivariant $K$-theory is a generalized equivariant cohomology theory which is a hybrid of the $K$-theory of a topological space and the representation theory of the group acting on it. In this article, we review the basics of equivariant…

K-Theory and Homology · Mathematics 2023-09-19 Chi-Kwong Fok

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…

Algebraic Topology · Mathematics 2018-01-31 J. P. C. Greenlees

A notion of stratification is introduced for any compactly generated triangulated category T endowed with an action of a graded commutative noetherian ring R. The utility of this notion is demonstrated by establishing diverse consequences…

Category Theory · Mathematics 2014-02-26 Dave Benson , Srikanth B. Iyengar , Henning Krause

In the framework of locally covariant quantum field theory, a theory is described as a functor from a category of spacetimes to a category of *-algebras. It is proposed that the global gauge group of such a theory can be identified as the…

Mathematical Physics · Physics 2013-09-13 Christopher J. Fewster

We prove that the derived category of $R$-linear representations of a finite group $G$ is stratified for any regular commutative ring $R$. As an application, we obtain a classification of localizing tensor ideals of ordinary $R$-linear…

Algebraic Topology · Mathematics 2022-03-31 Tobias Barthel

Functions which are equivariant or invariant under the transformations of a compact linear group $G$ acting in an euclidean space $\real^n$, can profitably be studied as functions defined in the orbit space of the group. The orbit space is…

Mathematical Physics · Physics 2009-11-10 G. Sartori , G. Valente

This article provides a geometric bridge between two entirely different character formulas for reductive Lie groups and answers the question posed by W.Schmid in [Sch]. A corresponding problem in the compact group setting was solved by…

Representation Theory · Mathematics 2007-05-23 Matvei Libine

In this paper, we study continuous Rokhlin property of $\mathrm{C}^*$-dynamical systems using techniques of equivariant $\mathrm{KK}$-theory and quantum group theory. In particular, we determine the $\mathrm{KK}$-equivalence class and give…

Operator Algebras · Mathematics 2015-12-22 Yuki Arano , Yosuke Kubota

We consider the equivariant Kasparov category associated to an \'etale groupoid, and by leveraging its triangulated structure we study its localization at the "weakly contractible" objects, extending previous work by R. Meyer and R. Nest.…

K-Theory and Homology · Mathematics 2024-12-23 Christian Bönicke , Valerio Proietti

We apply equivariant localization to supersymmetric quantum mechanics and show that the partition function localizes on the instantons of the theory. Our construction of equivariant cohomology for SUSY quantum mechanics is different than…

High Energy Physics - Theory · Physics 2007-05-23 Levent Akant

In this note, we study equivariant versions of Stolz' $R$-groups, the positive scalar curvature structure groups $R^{\rm spin}_n(X)^G$, for proper actions of discrete groups $G$. We define the concept of a fundamental groupoid functor for a…

Geometric Topology · Mathematics 2025-11-03 Massimiliano Puglisi , Thomas Schick , Vito Felice Zenobi

We present a quick approach to computing the $K$-theory of the category of locally compact modules over any order in a semisimple $\mathbb{Q}$-algebra. We obtain the $K$-theory by first quotienting out the compact modules and subsequently…

K-Theory and Homology · Mathematics 2020-06-22 Oliver Braunling , Ruben Henrard , Adam-Christiaan van Roosmalen

We propose a construction of an analogue of the Hill-Hopkins-Ravenel relative norm $N_{H}^{G}$ in the context of a positive dimensional compact Lie group $G$ and closed subgroup $H$. We explore expected properties of the construction. We…

Algebraic Topology · Mathematics 2022-12-23 Andrew J. Blumberg , Michael A. Hill , Michael A. Mandell

Suppose that $X=G/K$ is the quotient of a locally compact group by a closed subgroup. If $X$ is locally contractible and connected, we prove that $X$ is a manifold. If the $G$-action is faithful, then $G$ is a Lie group.

Group Theory · Mathematics 2013-07-23 Karl H. Hofmann , Linus Kramer

Let $X$ be a connected complex manifold equipped with a holomorphic action of a complex Lie group $G$. We investigate conditions under which a principal bundle on $X$ admits a $G$--equivariance structure.

Complex Variables · Mathematics 2016-11-29 Indranil Biswas , Arjun Paul

We establish a novel approach to computing $G$-equivariant cohomology for a finite group $G$, and demonstrate it in the case that $G = C_{p^n}$. For any commutative ring spectrum $R$, we prove a symmetric monoidal reconstruction theorem for…

Algebraic Topology · Mathematics 2023-04-03 David Ayala , Aaron Mazel-Gee , Nick Rozenblyum

Let $G$ be a group and let $E$ be a functor from small $\Z$-linear categories to spectra. Also let $A$ be a ring with a $G$-action. Under mild conditions on $E$ and $A$ one can define an equivariant homology theory of $G$-simplicial sets…

K-Theory and Homology · Mathematics 2014-03-06 Guillermo Cortiñas , Eugenia Ellis

Exact categories are a natural generalisation of abelian categories and provide a fertile ground to develop relative homological algebra. In this paper, starting from a class of relative Gorenstein projective objects in an exact category…

Representation Theory · Mathematics 2026-02-27 Anastasios Slaftsos , Jorge Vitória