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We study the behavior of the Nil-subgroups of K-groups under localization. As a consequence we obtain that the relative assembly map from the family of finite subgroups to the family of virtually cyclic subgroups is rationally an…

K-Theory and Homology · Mathematics 2007-05-23 Joachim Grunewald

A theory of Clebsch-Gordan coefficients for $SL(2, C)$ is given using only rational numbers. Features include orthogonality relations, recurrence relations, and Regge's symmetry group. Results follow from elementary representation theory…

Representation Theory · Mathematics 2021-10-28 Robert W. Donley , Won Geun Kim

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

We offer a short proof of Connes' Hochschild class of the Chern character formula for non-unital semifinite spectral triples. The proof is simple due to its reliance on the authors' extensive work on a refined version of the local index…

K-Theory and Homology · Mathematics 2018-05-02 Alan L. Carey , A. Rennie

We introduce parabolic degenerations of rational Cherednik algebras of complex reflection groups, and use them to give necessary conditions for finite-dimensionality of an irreducible lowest weight module for the rational Cherednik algebra…

Representation Theory · Mathematics 2015-03-02 Stephen Griffeth , Armin Gusenbauer , Daniel Juteau , Martina Lanini

In this paper, following an elementary line of thought which somewhat differs from the usual one, we prove once more that any deterministic theory predictively equivalent to quantum mechanics unavoidably exhibits a contextual character. The…

Quantum Physics · Physics 2009-11-13 GianCarlo Ghirardi , Karl Wienand

This survey article on bivariant Kasparov theory and E-theory is mainly intended for readers with a background in homotopical algebra and category theory. We approach both bivariant K-theories via their universal properties and equip them…

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

In this paper, we define a stringy product on $K^*_{orb}(\XX) \otimes \C $, the orbifold K-theory of any almost complex presentable orbifold $\XX$. We establish that under this stringy product, the de-locaized Chern character ch_{deloc} :…

Algebraic Topology · Mathematics 2012-05-17 Jianxun Hu , Bai-Ling Wang

We prove a noncommutative variant of Saskin's classical theorem -- on the connection between Choquet boundaries for function spaces and Korovkin sets -- for operator systems generating separable Type I C*-algebras. The main result implies…

Operator Algebras · Mathematics 2015-05-22 Craig Kleski

We investigate the notion of Connes-amenability for dual Banach algebras, as introduced by Runde, for bidual algebras and weighted semigroup algebras. We provide some simplifications to the notion of a $\sigma WC$-virtual diagonal, as…

Functional Analysis · Mathematics 2010-03-16 Matthew Daws

In this article we construct explicit cocycles in the Alexander-Spanier cohomological complex, representing the Chern character of an element in K-theory.

K-Theory and Homology · Mathematics 2007-05-23 Alexander Gorokhovsky

Let $G$ be a finite group, $k$ be a field and $G\to GL(V_{\rm reg})$ be the regular representation of $G$ over $k$. Then $G$ acts naturally on the rational function field $k(V_{\rm reg})$ by $k$-automorphisms. Define $k(G)$ to be the fixed…

Algebraic Geometry · Mathematics 2019-09-26 Akinari Hoshi , Ming-chang Kang , Aiichi Yamasaki

We show that for various natural classes of groups and appropriately defined K- and L-theoretic functors, injectivity or bijectivity of the assembly map follows from the Isomorphism Conjecture being true for acyclic groups lying within that…

K-Theory and Homology · Mathematics 2017-03-07 Crichton Ogle , Shengkui Ye

Let $X$ be a compact Hausdorff space, let $\Gamma$ be a discrete group that acts continuously on $X$ from the right, define $\widetilde{X} = \{(x,\gamma) \in X \times \Gamma : x\cdot\gamma= x\}$, and let $\Gamma$ act on $\widetilde{X}$ via…

K-Theory and Homology · Mathematics 2010-11-01 Efton Park

We define an equivariant $K_0$-theory for \textit{Yetter-Drinfeld} algebras over a Hopf algebra with an invertible antipode. We then show that this definition can be generalized to all Hopf-module algebras. We show that there exists a…

K-Theory and Homology · Mathematics 2007-05-23 R. Akbarpour , M. Khalkhali

The Kirchberg Embedding Problem (KEP) asks if every C*-algebra embeds into an ultrapower of the Cuntz algebra $\mathcal{O}_2$. In an effort to provide a negative solution to the KEP and motivated by the recent refutation of the Connes…

Logic · Mathematics 2023-03-07 Alec Fox , Isaac Goldbring , Bradd Hart

We present a short proof, based on local character expansions, of the celebrated theorem of Harish-Chandra about local integrability of complex characters of $p$-adic reductive groups. The proof gives an algebraic incarnation of the local…

Representation Theory · Mathematics 2026-04-17 Cheng-Chiang Tsai

In this paper we identify many striking elements in Leibniz (co)homology which arise from characteristic classes and K-theory. For a group G a field k of characteristic zero, it is shown that all primary characteristic classes, i.e. H^*(BG;…

K-Theory and Homology · Mathematics 2007-05-23 Jerry Lodder

Classical Chern-Weil theory proves existence of a ring homomorphism - the Chern character - from the Grothendieck ring of locally free finite rank A-modules to the algebraic de Rham cohomology of A. In this paper we prove existence of a…

Algebraic Geometry · Mathematics 2020-11-13 Helge Øystein Maakestad

Meyer and Nest showed that the Baum--Connes map is equivalent to a map on $K$-theory of two different crossed products. This approach is strongly categorial in method since its bases is to regard Kasparov's theory $KK^G$ as a triangulated…

K-Theory and Homology · Mathematics 2017-07-13 Bernhard Burgstaller