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Related papers: On a quantitative operator K-theory

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In a recent paper, Pardo and the first named author introduced a class of C*-algebras which which are constructed from an action of a group on a graph. This class was shown to include many C*-algebras of interest, including all Kirchberg…

Operator Algebras · Mathematics 2014-06-30 Ruy Exel , Charles Starling

We prove the existence of a strict deformation quantization for the canonical Poisson structure on the dual of an integrable Lie algebroid. It follows that any Lie groupoid C*-algebra may be regarded as a result of a quantization procedure.…

Mathematical Physics · Physics 2007-05-23 N. P. Landsman , B. Ramazan

Using the Evans spectral sequence and its counter-part for real $K$-theory, we compute both the real and complex $K$-theory of several infinite families of $C^*$-algebras based on higher-rank graphs of rank $3$ and $4$. The higher-rank…

Operator Algebras · Mathematics 2025-02-26 Jeffrey L Boersema , Alina Vdovina

We compute the K-theory for C*-algebras naturally associated with rings of integers in number fields. The main ingredient is a duality theorem for arbitrary global fields. It allows us to identify the crossed product arising from affine…

Operator Algebras · Mathematics 2009-06-29 Joachim Cuntz , Xin Li

We give a decomposition of the equivariant Kasparov category for discrete quantum group with torsions. As an outcome, we show that the crossed product by a discrete quantum group in a certain class preserves the UCT. We then show that…

Operator Algebras · Mathematics 2021-03-22 Yuki Arano , Adam Skalski

We develop an Eilenberg-Moore spectral sequence to compute Bredon cohomology of spaces with an action of a group given as a pullback. Using several other spectral sequences, and positive results on the Baum-Connes Conjecture, we are able to…

K-Theory and Homology · Mathematics 2014-08-19 Noe Barcenas , Daniel Juan-Pineda , Mario Velasquez

To an arbitrary directed graph we associate a row-finite directed graph whose C*-algebra contains the C*-algebra of the original graph as a full corner. This allows us to generalize results for C*-algebras of row-finite graphs to…

Operator Algebras · Mathematics 2007-05-23 D. Drinen , M. Tomforde

We compute the K-theory of the Cuntz-Krieger C^*-algebras associated to infinite matrices.

Operator Algebras · Mathematics 2007-05-23 Ruy Exel , Marcelo Laca

We determine the $K$-theory of the $C^{*}$-algebra $C(SU_{-1}(2))$ and describe its spectrum. Moreover, we exhibit a continuous $C^{*}$-bundle over $[-1,0)$ whose fibre at $q$ is isomorphic to $C(SU_{q}(2))$.

Operator Algebras · Mathematics 2015-03-06 Selcuk Barlak

We complete the classification of Bost--Connes systems. We show that two Bost--Connes C*-algebras for number fields are isomorphic if and only if the original semigroups actions are conjugate. Together with recent reconstruction results in…

Operator Algebras · Mathematics 2018-07-16 Yosuke Kubota , Takuya Takeishi

We investigate the relations between the Grothendieck group of coherent modules of an algebraic variety and its Chow group of algebraic cycles modulo rational equivalence. Those are in essence torsion phenomena, which we attempt to control…

Algebraic Geometry · Mathematics 2023-08-29 Olivier Haution , Alexander S. Merkurjev

We realize Kellendonk'?s C*-algebra of an aperiodic tiling as the tight C*-algebra of the inverse semigroup associated to the tiling, thus providing further evidence that the tight C*-algebra is a good candidate to be the natural…

Operator Algebras · Mathematics 2011-06-23 Ruy Exel , Daniel Gonçalves , Charles Starling

We document some versions, in real K-theory, of well-known properties of the coarse assembly map in complex K-theory. These results are well-known, but difficult to find in the literature.

K-Theory and Homology · Mathematics 2013-08-13 John Roe

In this paper, we will follow Kirchberg's categorical perspective to establish new notions of WEP and QWEP relative to a C$^*$-algebra, and develop similar properties as in the classical WEP and QWEP. Also we will show some examples of…

Operator Algebras · Mathematics 2014-10-21 Jian Liang , Sepideh Rezvani

Strongly self-absorbing $\mathrm{C}^*$-algebras play a distinguished role in the classification of nuclear $\mathrm{C}^*$-algebras. Their dynamical analogues were introduced and extensively studied by Szab\'o. In this paper, we propose a…

Operator Algebras · Mathematics 2026-03-16 Masaki Izumi , Keiya Ohara

We revisit the computation, due to Hesselholt and Madsen, of the K-theory of truncated polynomial algebras for perfect fields of positive characteristic. The resulting K-groups are expressed in terms of big Witt vectors of the field. The…

K-Theory and Homology · Mathematics 2020-03-02 Martin Speirs

It is shown that the pairing of the K00 group of a C*-algebra with the densely defined traces of the algebra can be extended to a pairing with the densely defined weights. For traces the pairing can be extended to the K0 group without the…

Operator Algebras · Mathematics 2024-03-15 Klaus Thomsen

To a large class of graphs of groups we associate a C*-algebra universal for generators and relations. We show that this C*-algebra is stably isomorphic to the crossed product induced from the action of the fundamental group of the graph of…

Operator Algebras · Mathematics 2021-07-27 Nathan Brownlowe , Alexander Mundey , David Pask , Jack Spielberg , Anne Thomas

In this note we set a configuration space description of the equivariant connective K-homology groups with coefficients in a unital C*-algebra for proper actions. Over this model we define a connective assembly map and prove that in this…

K-Theory and Homology · Mathematics 2019-02-04 Mario Velásquez

Motivated by classical facts concerning closed manifolds, we introduce a strong finiteness property in K-homology. We say that a C*-algebra has uniformly summable K-homology if all its K-homology classes can be represented by Fredholm…

Operator Algebras · Mathematics 2015-12-16 Heath Emerson , Bogdan Nica