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We prove a generalization of the fundamental theorem of algebraic K-theory for Verdier-localizing functors by extending the proof for algebraic K-theory of spaces to the realm of stable $\infty$-categories. The formula behaves much better…

K-Theory and Homology · Mathematics 2023-12-06 Victor Saunier

We prove a general form of the statement that the cohomology of a quotient stack can be computed by the Borel construction. It also applies to the lisse extensions of generalized cohomology theories like motivic cohomology and algebraic…

Algebraic Geometry · Mathematics 2025-09-29 Adeel A. Khan , Charanya Ravi

In this article we describe the $G\times G$-equivariant $K$-ring of $X$, where $X$ is a regular compactification of a connected complex reductive algebraic group $G$. Furthermore, in the case when $G$ is a semisimple group of adjoint type,…

Algebraic Geometry · Mathematics 2007-06-12 V. Uma

We provide a fairly self-contained account of the localisation and cofinality theorems for the algebraic $\mathrm{K}$-theory of stable $\infty$-categories. It is based on a general formula for the evaluation of an additive functor on a…

K-Theory and Homology · Mathematics 2023-03-15 Fabian Hebestreit , Andrea Lachmann , Wolfgang Steimle

In this article we describe the $\tG\times \tG$-equivariant $K$-ring of $X$, where $\tG$ is a {\it factorial} cover of a connected complex reductive algebraic group $G$, and $X$ is a regular compactification of $G$. Furthermore, using the…

Algebraic Geometry · Mathematics 2014-09-12 V. Uma

We compute the equivariant complex K-theory ring of a cohomogeneity-one action of a compact Lie group at the level of generators and relations and derive a characterization of K-theoretic equivariant formality for these actions. Less…

Algebraic Topology · Mathematics 2022-03-15 Jeffrey D. Carlson

The goal of this paper is to prove a version of the non-abelian localization theorem for the rational equivariant K-theory of a smooth variety $X$ with the action of a linear algebraic group $G$. We then use this to prove a Riemann-Roch…

Algebraic Geometry · Mathematics 2009-06-16 Amalendu Krishna

A. Vistoli proved a decomposition theorem for the rational equivariant algebraic K-theory of a variety under the action of a finite group $G$. We generalize his result to more general algebraic (co)homology theories having the Mackey…

Algebraic Geometry · Mathematics 2025-05-21 Francesco Sala

The problem of equivariant rigidity is the $\Gamma$-homeomorphism classification of $\Gamma$-actions on manifolds with compact quotient and with contractible fixed sets for all finite subgroups of $\Gamma$. In other words, this is the…

Geometric Topology · Mathematics 2015-12-15 Frank Connolly , James F. Davis , Qayum Khan

We consider infinite tensor product actions of $G = \mathbb{Z}/p\mathbb{Z}$ on the UHF-algebra $D = \text{End}(V)^{\otimes \infty}$ for a finite-dimensional unitary $G$-representation $V$ and determine the equivariant homotopy type of the…

Algebraic Topology · Mathematics 2024-10-10 Valerio Bianchi , Ulrich Pennig

Let $k$ be a field of characteristic zero and ${\bar k}$ an algebraic closure of $k$. For a geometrically integral variety $X$ over $k$, we write ${\bar k}(X)$ for the function field of ${\bar X}=X\times_k{\bar k}$. If $X$ has a smooth…

Number Theory · Mathematics 2021-03-08 M. Borovoi , J-L. Colliot-Thélène , A. N. Skorobogatov

We generalize two classical homotopy theory results, the Blakers-Massey Theorem and Quillen's Theorem B, to G-equivariant cubical diagrams of spaces, for a discrete group G. We show that the equivariant Freudenthal suspension Theorem for…

Algebraic Topology · Mathematics 2016-05-04 Emanuele Dotto

We prove that for the action of a finite constant group scheme, equivariant algebraic $K$-theory is represented by a colimit of Grassmannians in the equivariant motivic homotopy category. Using this result we show that the set of…

Algebraic Geometry · Mathematics 2025-08-15 K. Arun Kumar , Girja S Tripathi

We compute the $RO(A)$-graded coefficients of $A$-equivariant complex and real topological $K$-theory for $A$ a finite elementary abelian $2$-group, together with all products, transfers, restrictions, power operations, and Adams…

Algebraic Topology · Mathematics 2022-10-12 William Balderrama

The smooth action of a compact Lie group on a compact manifold can be resolved to an iterated space, as made explicit by Pierre Albin and the second author. On the resolution the lifted action has fixed isotropy type corresponding to the…

K-Theory and Homology · Mathematics 2021-01-05 Panagiotis Dimakis , Richard Melrose

In this paper we study a natural decomposition of $G$-equivariant $K$-theory of a proper $G$-space, when $G$ is a Lie group with a compact normal subgroup $A$ acting trivially. Our decomposition could be understood as a generalization of…

Algebraic Topology · Mathematics 2024-09-10 Andrés Angel , Edward Becerra , Mario Velásquez

For $G$ a finite group, a normalized 2-cocycle $\alpha\in Z^{2}\big(G,{\mathbb S}^{1}\big)$ and $X$ a $G$-space on which a normal subgroup $A$ acts trivially, we show that the $\alpha$-twisted $G$-equivariant $K$-theory of $X$ decomposes as…

Algebraic Topology · Mathematics 2021-04-22 José Manuel Gómez , Johana Ramírez

Let G denote a compact connected Lie group with torsion-free fundamental group acting on a compact space X such that all the isotropy subgroups are connected subgroups of maximal rank. Let $T\subset G$ be a maximal torus with Weyl group W.…

Algebraic Topology · Mathematics 2014-02-26 Alejandro Adem , José Manuel Gómez

We prove that each exponential functor on the category of finite-dimensional complex inner product spaces and isomorphisms gives rise to an equivariant higher (ie. non-classical) twist of $K$-theory over $G=SU(n)$. This twist is represented…

K-Theory and Homology · Mathematics 2022-06-29 David E. Evans , Ulrich Pennig

Bivariant (equivariant) K-theory is the standard setting for non-commutative topology. We may carry over various techniques from homotopy theory and homological algebra to this setting. Here we do this for some basic notions from…

K-Theory and Homology · Mathematics 2015-10-23 Ralf Meyer , Ryszard Nest