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Let $G$ be a connected semisimple Lie group with its maximal compact subgroup $K$ being simply-connected. We show that the twisted equivariant $KK$-theory $KK^{\bullet}_{G}(G/K, \tau_G^G)$ of $G$ has a ring structure induced from the…

K-Theory and Homology · Mathematics 2021-06-30 Chi-Kwong Fok , Varghese Mathai

Let $S$ be a finite dimensional noetherian scheme. For any proper morphism between smooth $S$-schemes, we prove a Riemann-Roch formula relating higher algebraic $K$-theory and motivic cohomology, thus with no projective hypothesis neither…

Algebraic Topology · Mathematics 2017-05-31 A. Navarro , J. Navarro

We show that the hermitian K-theory space of a commutative ring R can be identified, up to A^1-homotopy, with the group completion of the groupoid of oriented finite Gorenstein R-algebras, i.e., finite locally free R-algebras with…

Algebraic Geometry · Mathematics 2022-09-14 Marc Hoyois , Joachim Jelisiejew , Denis Nardin , Maria Yakerson

A group action on the input ring or category induces an action on the algebraic $K$-theory spectrum. However, a shortcoming of this naive approach to equivariant algebraic $K$-theory is, for example, that the map of spectra with $G$-action…

Algebraic Topology · Mathematics 2016-09-14 Mona Merling

A new approach to \'etale homotopy theory is presented which applies to a much broader class of objects than previously existing approaches, namely it applies not only to all schemes (without any local Noetherian hypothesis), but also to…

Algebraic Geometry · Mathematics 2016-07-27 David Carchedi

We construct an abelian category A(G) of sheaves over a category of closed subgroups of the r-torus G and show it is of finite injective dimension. It can be used as a model for rational $G$-spectra in the sense that there is a homology…

Algebraic Topology · Mathematics 2007-05-23 J. P. C. Greenlees

If A is a homotopy cartesian square of ring spectra satisfying connectivity hypotheses, then the cube induced by Goodwillie's integral cyclotomic trace from K(A) to TC(A) is homotopy cartesian. In other words, the homotopy fiber of the…

Algebraic Topology · Mathematics 2022-08-24 Bjørn Ian Dundas , Harald Øyen Kittang

In the Morel-Voevodsky motivic stable homotopy category of a quasi-compact quasi-separated scheme S, several candidates exist for a motivic spectrum representing hermitian K-theory. This note shows that the cellular absolute motivic…

K-Theory and Homology · Mathematics 2025-07-16 K. Arun Kumar , Oliver Röndigs

In this paper, we build on the work from our previous paper (arXiv:2002.01556) to show that periodic rational $G$-equivariant topological $K$-theory has a unique genuine-commutative ring structure for $G$ a finite abelian group. This means…

Algebraic Topology · Mathematics 2021-04-05 Anna Marie Bohmann , Christy Hazel , Jocelyne Ishak , Magdalena Kędziorek , Clover May

We prove absolute purity for the rational motivic sphere spectrum. The main ingredient is the construction of an analogue of the Chern character, where algebraic K-theory is replaced by hermitian K-theory, and motivic cohomology by the plus…

Algebraic Geometry · Mathematics 2019-02-07 Frédéric Déglise , Jean Fasel , Fangzhou Jin , Adeel Khan

Let G be a reductive affine group scheme defined over a semilocal ring k. Assume that either G is semisimple or k is normal and noetherian. We show that G has a finite k-subgroup S such that the natural map H^1(R, S) --> H^1(R, G) is…

Algebraic Geometry · Mathematics 2009-07-06 V. Chernousov , Ph. Gille , Z. Reichstein

Let $G$ be a complex connected reductive algebraic group that acts on a smooth complex algebraic variety $X$, and let $E$ be a $G$-equivariant algebraic vector bundle over $X$. A section of $E$ is regular if it is transversal to the zero…

Algebraic Topology · Mathematics 2021-05-06 Alexey Gorinov , Nikolay Konovalov

Let V be a smooth variety defined over the real numbers. Every algebraic vector bundle on V induces a complex vector bundle on the underlying topological space V(C), and the involution coming from complex conjugation makes it a Real vector…

K-Theory and Homology · Mathematics 2007-05-23 Max Karoubi , Charles Weibel

Let $(G,K)$ be a Riemannian symmetric pair of maximal rank, where $G$ is a compact simply connected Lie group and $K$ the fixed point set of an involutive automorphism $\sigma$. This induces an involutive automorphism $\tau$ of the based…

Differential Geometry · Mathematics 2009-09-11 Lisa C. Jeffrey , Augustin-Liviu Mare

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

We construct a surjective homomorphism from Somekawa's K-group associated to a finite collection of semi-abelian varieties over a perfect field to a corresponding Hom group in Voevodsky's triangulated category of effective motivic…

Algebraic Geometry · Mathematics 2010-09-24 Bruno Kahn

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

We construct multiplicative norms on equivariant nonconnective algebraic $K$-theory for finite groups $G$. We also construct a genuine equivariant version of THH equipped with a Dennis trace map from K-theory compatible with the…

K-Theory and Homology · Mathematics 2026-03-18 Kaif Hilman , Maxime Ramzi

We study the algebraic $K$-theory of rings of the form $R[x]/x^e$. We do this via trace methods and filtrations on topological Hochschild homology and related theories by quasisyntomic sheaves. We produce computations for $R$ a perfectoid…

K-Theory and Homology · Mathematics 2023-05-08 Noah Riggenbach

For a Lie algebroid pair $A\hookrightarrow L$ we study cocycles constructed from the extension to $L$ of the higher connection forms of a representation up to homotopy $E$ of the Lie algebroid $A$. We show that there exists a cohomology…

Differential Geometry · Mathematics 2024-06-11 Panagiotis Batakidis , Sylvain Lavau