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Related papers: On a quantitative operator K-theory

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We interpret certain equivariant Kasparov groups as equivariant representable K-theory groups. We compute these groups via a classifying space and as K-theory groups of suitable sigma-C*-algebras. We also relate equivariant vector bundles…

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

For a long time, practitioners of the art of operator algebras always worked over the complex numbers, and nobody paid much attention to real C*-algebras. Over the last thirty years, that situation has changed, and it's become apparent that…

Operator Algebras · Mathematics 2016-08-16 Jonathan Rosenberg

In this paper we describe the C*-algebras associated to the Baumslag-Solitar groups with the ordering defined by the usual presentations. These are Morita equivalent to the crossed product C*-algebras obtained by letting the group act on…

Operator Algebras · Mathematics 2012-11-16 Jack Spielberg

We construct a sequence of $n-1$ cyclic exact sequences that can be used to compute the $K$-theory of the $C^\star$-algebra crossed product $A \ltimes {\mathbb Z}_n$.

Operator Algebras · Mathematics 2015-05-11 Larry B. Schweitzer

A covering of k-graphs (in the sense of Pask-Quigg-Raeburn) induces an embedding of universal C*-algebras. We show how to build a (k+1)-graph whose universal algebra encodes this embedding. More generally we show how to realise a direct…

Operator Algebras · Mathematics 2008-05-29 Alex Kumjian , David Pask , Aidan Sims

We initiate the study of computable presentations of real and complex C*-algebras under the program of effective metric structure theory. With the group situation as a model, we develop corresponding notions of recursive presentations and…

Logic · Mathematics 2023-04-17 Alec Fox

We consider a construction of C*-algebras from continuous piecewise monotone maps on the circle which generalizes the crossed product construction for homeomorphisms and more generally the construction of Renault, Deaconu and…

Operator Algebras · Mathematics 2019-02-20 Thomas L. Schmidt , Klaus Thomsen

We define united KK-theory for real C*-algebras A and B such that A is separable and B is sigma-unital, extending united K-theory in the sense that KK\crt(\R, B) = K\crt(B). United KK-theory contains real, complex, and self-conjugate…

Operator Algebras · Mathematics 2007-05-23 Jeffrey L. Boersema

In this work we construct a C*-algebra from an injective endomorphisms of some group G, allowing the endomorphism to have infinite cokernel. We generalize results obtained by I. Hirshberg and also by J. Cuntz and A. Vershik. In good cases…

Functional Analysis · Mathematics 2018-03-13 Felipe Vieira

We present and study C*-algebras generated by "periodic weighted creation operators" on the Fock space associated with an automorphism $\alpha$ on a C*-algebra $A$. These algebras can be viewed as generalized Bunce-Deddens algebras…

Operator Algebras · Mathematics 2007-05-23 Baruch Solel

In this paper we provide descriptions of the Whitehead groups with coefficients in a ring of the Hilbert modular group and its reduced version, as well as for the topological K-theory of $C^*$-algebras, after tensoring with $\mathbb{Q}$, by…

K-Theory and Homology · Mathematics 2017-06-16 Luis Jorge Sánchez Saldaña , Mario Velásquez

We study general properties of exotic crossed-product functors and characterise those which extend to functors on equivariant C*-algebra categories based on correspondences. We show that every such functor allows the construction of a…

Operator Algebras · Mathematics 2015-07-07 Alcides Buss , Siegfried Echterhoff , Rufus Willett

We provide a complete classification of the class of unital graph $C^*$-algebras - prominently containing the full family of Cuntz-Krieger algebras - showing that Morita equivalence in this case is determined by ordered, filtered…

Operator Algebras · Mathematics 2021-09-20 Søren Eilers , Gunnar Restorff , Efren Ruiz , Adam P. W. Sørensen

We exhibit a countably infinite family of simple, separable, nuclear, and mutually non-isomorphic C*-algebras which agree on K-theory and traces. The algebras do not absorb the Jiang-Su algebra Z tensorially, answering a question of N. C.…

Operator Algebras · Mathematics 2007-08-22 Andrew S. Toms

We formalize the quantum arithmetic, i.e. a relationship between number theory and operator algebras. Namely, it is proved that rational projective varieties are dual to the $C^*$-algebras with real multiplication. Our construction fits all…

Number Theory · Mathematics 2024-12-13 Igor V. Nikolaev

Noncommutative lattices have been recently used as finite topological approximations in quantum physical models. As a first step in the construction of bundles and characteristic classes over such noncommutative spaces, we shall study their…

q-alg · Mathematics 2008-02-03 Elisa Ercolessi , Giovanni Landi , Paulo Teotonio-Sobrinho

This is a survey on Kasparov's bivariant $KK$-theory in connection with the Baum-Connes conjecture on the $K$-theory of crossed products $A\rtimes_rG$ by actions of a locally compact group $G$ on a C*-algebra $A$. In particular we shall…

K-Theory and Homology · Mathematics 2017-06-14 Siegfried Echterhoff

It is determined exactly which classifiable C*-algebras have approximately inner flip. The answer includes a number of C*-algebras with torsion in their K-theory, and a number of C*-algebras that are self-absorbing but not strongly…

Operator Algebras · Mathematics 2016-01-11 Aaron Tikuisis

We use homotopy theoretic ideas to study the $K$-theory of (graded, Real) $C^*$-algebras in detail. After laying the foundations, and deriving the formal properties, the comparison of the model with the Kasparov picture of $K$-theory has…

K-Theory and Homology · Mathematics 2024-10-30 Anupam Datta

We develop methods for computing graded K-theory of C*-algebras as defined in terms of Kasparov theory. We establish graded versions of Pimsner's six-term sequences for graded Hilbert bimodules whose left action is injective and by…

Operator Algebras · Mathematics 2017-06-05 Alex Kumjian , David Pask , Aidan Sims