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Related papers: Completion theorem for equivariant $K$-theory

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We compute the equivariant K-theory with integer coefficients of an equivariantly formal isotropy action, subject to natural hypotheses which cover the three major classes of known examples. The proof proceeds by constructing a map of…

Algebraic Topology · Mathematics 2023-11-28 Jeffrey D. Carlson

We describe Universal Coefficient Theorems for the equivariant Kasparov theory for C*-algebras with an action of the group of integers or over a unique path space, using KK-valued invariants. We compare the resulting classification up to…

K-Theory and Homology · Mathematics 2020-11-04 Ralf Meyer

We show that there is a stable homotopy theory of profinite spaces and use it for two main applications. On the one hand we construct an \'etale topological realization of the stable motivic homotopy theory of smooth schemes over a base…

Algebraic Geometry · Mathematics 2007-06-13 Gereon Quick

We find the model completion of the theory modules over $A$, where $A$ is a finitely generated commutative algebra over a field $K$. This is done in a context where the field $K$ and the module are represented by sorts in the theory, so…

Logic · Mathematics 2009-08-05 Moshe Kamensky

We compute the equivariant $K$-theory $K_G^*(G)$ for a simply connected Lie group $G$ (acting on itself by conjugation). We prove that $K_G^*(G)$ is isomorphic to the algebra of Grothendieck differentials on the representation ring. We also…

dg-ga · Mathematics 2007-05-23 Jean-Luc Brylinski , Bin Zhang

We prove an equivariant Riemann-Roch formula for divisors on algebraic curves over perfect fields. By reduction to the known case of curves over algebraically closed fields, we first show a preliminary formula with coefficients in Q. We…

Algebraic Geometry · Mathematics 2008-04-11 Helena B. Fischbacher-Weitz , Bernhard Köck

The K\"unneth Theorem for equivariant (complex) K-theory K^*_G, in the form developed by Hodgkin and others, fails dramatically when G is a finite group, and even when G is cyclic of order 2. We remedy this situation in this very simplest…

K-Theory and Homology · Mathematics 2014-10-01 Jonathan Rosenberg

In the two parts of this paper we solve a problem of De Rham, proving that Reidemeister torsion invariants determine topological equivalence of linear G-representations, for G a finite cyclic group. Methods in controlled K-theory and…

Geometric Topology · Mathematics 2013-02-12 Ian Hambleton , Erik K. Pedersen

We construct a semi-orthogonal decomposition on the category of perfect complexes on the blow-up of a derived Artin stack in a quasi-smooth centre. This gives a generalization of Thomason's blow-up formula in algebraic K-theory to derived…

K-Theory and Homology · Mathematics 2020-09-15 Adeel A. Khan

We prove the following generalization of the classical Shephard-Todd-Chevalley Theorem. Let $G$ be a finite group of graded algebra automorphisms of a skew polynomial ring $A:=k_{p_{ij}}[x_1,...,x_n]$. Then the fixed subring $A^G$ has…

Rings and Algebras · Mathematics 2008-06-20 E. Kirkman , J. Kuzmanovich , J. J. Zhang

Working in the context of symmetric spectra, we describe and study a homotopy completion tower for algebras and left modules over operads in the category of modules over a commutative ring spectrum (e.g., structured ring spectra). We prove…

Algebraic Topology · Mathematics 2014-11-11 John E. Harper , Kathryn Hess

In equivariant geometry, a localization (a.k.a., concentration) theorem is typically interpreted as a relationship between the equivariant geometry of a space with a group action and the geometry of its fixed locus. We take a different…

Algebraic Geometry · Mathematics 2025-11-06 Daniel Halpern-Leistner

Let G be a discrete group. We give methods to compute for a generalized (co-)homology theory its values on the Borel construction (EG x X)/G of a proper G-CW-complex X satisfying certain finiteness conditions. In particular we give formulas…

K-Theory and Homology · Mathematics 2012-01-24 Michael Joachim , Wolfgang Lueck

We prove a result about the non-existence of certain sums-of-squares formulas over a field. This generalizes an old theorem which used topological K-theory to obtain obstruction conditions when the field is the real numbers. Our result…

Algebraic Topology · Mathematics 2007-05-23 Daniel Dugger , Daniel C. Isaksen

We study a variant of algebraic K-theory and prove that it is stable and preserves module structures.

Category Theory · Mathematics 2016-05-27 Sanath Devalapurkar

We construct geometric models for classifying spaces of linear algebraic groups in G-equivariant motivic homotopy theory, where G is a tame group scheme. As a consequence, we show that the equivariant motivic spectrum representing the…

K-Theory and Homology · Mathematics 2020-09-16 Marc Hoyois

The Algebraic Kirchberg-Phillips Question for Leavitt path algebras asks whether unital $K$-theory is a complete isomorphism invariant for unital, simple, purely infinite Leavitt path algebras over finite graphs. Most work on this problem…

Rings and Algebras · Mathematics 2024-07-30 Efren Ruiz

We show that if G is a split semisimple algebraic group over a model complete field K, then the groups G(K) and G(K)' (the commutator group which is a ``Chevalley group'' as for example the group PSL_2(K)) are model complete as well.

Logic · Mathematics 2025-03-04 Daniel Max Hoffmann , Piotr Kowalski , Chieu-Minh Tran , Jinhe Ye

We consider the problem of smoothing algebraic cycles with rational coefficients on smooth projective complex varieties up to homological equivalence. We show that a solution to this problem would be incompatible with the validity of the…

Algebraic Geometry · Mathematics 2024-10-22 Olivier Benoist , Claire Voisin

We generalize the functorial quasi-isomorphism in \cite{Davis2011} from overconvergent Witt de-Rham cohomology to rigid cohomology on smooth varieties over a finite field $k$, dropping the quasi-projectiveness condition. We do so by…

Number Theory · Mathematics 2018-10-25 Nathan Lawless