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We propose a generalization of K-theory to operator systems. Motivated by spectral truncations of noncommutative spaces described by $C^*$-algebras and inspired by the realization of the K-theory of a $C^*$-algebra as the Witt group of…

Operator Algebras · Mathematics 2024-09-05 Walter D. van Suijlekom

We investigate conditions on a graph $C^*$-algebra for the existence of a faithful semifinite trace. Using such a trace and the natural gauge action of the circle on the graph algebra, we construct a smooth $(1,\infty)$-summable semfinite…

Functional Analysis · Mathematics 2007-05-23 David Pask , Adam Rennie

We study the noncommutative geometry of algebras of Lipschitz continuous and H\"older continuous functions where non-classical and novel differential geometric invariants arise. Indeed, we introduce a new class of Hochschild and cyclic…

K-Theory and Homology · Mathematics 2023-06-21 Magnus Goffeng , Ryszard Nest

We define a categorical framework in which we build a systematic construction that provides generic invariants for C*-algebras. The benefit is significant as we show that any invariant arising this way automatically enjoys nice properties…

Operator Algebras · Mathematics 2023-09-06 Laurent Cantier

In this paper, a new invariant was built towards the classification of separable C*-algebras of real rank zero, which we call latticed total K-theory. A classification theorem is given in terms of such an invariant for a large class of…

Operator Algebras · Mathematics 2024-08-29 Qingnan An , Chunguang Li , Zhichao Liu

There are theories of coverings of $C^*$-algebras which can be included into a following list: coverings of commutative $C^*$-algebras, coverings of $C^*$-algebras of groupoids and foliations, coverings of noncommutative tori, the double…

Operator Algebras · Mathematics 2024-07-19 Petr Ivankov

We introduce a formulation of gauge theory on noncommutative spaces based on the concept of covariant coordinates. Some important examples are discussed in detail. A Seiberg-Witten map is established in all cases.

High Energy Physics - Theory · Physics 2011-09-13 John Madore , Stefan Schraml , Peter Schupp , Julius Wess

We expose a K-theoretic approach to study group C*-algebras and C*-algebraic compact quantum groups: 1. The conception of multidimensional geometric quantization and the index of group C*-algebras; 2. the entire homology of noncommutative…

K-Theory and Homology · Mathematics 2007-05-23 Do Ngoc Diep

We extend the spectral theory of commutative C*-categories to the non full-case, introducing a suitable notion of spectral spaceoid provinding a duality between a category of "non-trivial" *-functors of non-full commutative C*-categories…

Operator Algebras · Mathematics 2025-11-04 Paolo Bertozzini , Roberto Conti , Wicharn Lewkeeratiyutkul , Kasemsun Rutamorn

A general theory of the Frolicher-Nijenhuis and Schouten-Nijenhuis brackets in the category of modules over a commutative algebra is described. Some related structures and (co)homology invariants are discussed, as well as applications to…

Differential Geometry · Mathematics 2010-01-30 Iosif Krasil'shchik

This monograph studies $KK$-theory in its unbounded model. The central object is the $KK$-bordism group obtained by imposing the $KK$-bordism relation on unbounded $KK$-cycles. In the paradigm of noncommutative geometry, an unbounded…

K-Theory and Homology · Mathematics 2026-03-30 Robin J. Deeley , Magnus Goffeng , Bram Mesland

In this article we survey some of the recent goings-on in the classification programme of C$^*$-algebras, following the interesting link found between the Cuntz semigroup and the classical Elliott invariant and the fact that the Elliott…

Operator Algebras · Mathematics 2009-02-20 Pere Ara , Francesc Perera , Andrew S. Toms

For a large class of C*-algebras $A$, we calculate the $K$-theory of reduced crossed products $A^{\otimes G}\rtimes_rG$ of Bernoulli shifts by groups satisfying the Baum--Connes conjecture. In particular, we give explicit formulas for…

Operator Algebras · Mathematics 2022-10-18 Sayan Chakraborty , Siegfried Echterhoff , Julian Kranz , Shintaro Nishikawa

We associate to each unital $C^*$-algebra $A$ a geometric object---a diagram of topological spaces representing quotient spaces of the noncommutative space underlying $A$---meant to serve the role of a generalized Gel'fand spectrum. After…

Operator Algebras · Mathematics 2014-08-07 Nadish de Silva

We introduce a bivariant version of the Cuntz semigroup as equivalence classes of order zero maps generalizing the ordinary Cuntz semigroup. The theory has many properties formally analogous to KK-theory including a composition product. We…

Operator Algebras · Mathematics 2016-02-08 Joan Bosa , Gabriele Tornetta , Joachim Zacharias

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

A duality is discussed for Lie group bundles vs. certain tensor categories with non-simple identity, in the setting of Nistor-Troitsky gauge-equivariant K-theory. As an application, we study C*-algebra bundles with fibre a fixed-point…

K-Theory and Homology · Mathematics 2007-12-03 Ezio Vasselli

We show that the classification of the symmetric spaces can be achieved by K-theoretical methods. We focus on Hermitian symmetric spaces of non-compact type, and define K-theory for JB*-triples along the lines of C*-theory. K-groups have to…

Operator Algebras · Mathematics 2011-09-21 Dennis Bohle , Wend Werner

We discuss various aspects of noncommutative geometry of smooth subalgebras of Hensel-Steinitz algebras. In particular we study the structure of derivations and $K$-Theory of those smooth subalgebras.

Operator Algebras · Mathematics 2024-04-03 Shelley Hebert , Slawomir Klimek , Matt McBride , J. Wilson Peoples

The K-theoretic analog of Spanier-Whitehead duality for noncommutative C*-algebras is shown to hold for the Ruelle algebras associated to irreducible Smale spaces. This had previously been proved only for shifts of finite type. Implications…

K-Theory and Homology · Mathematics 2017-09-25 Jerome Kaminker , Ian F. Putnam , Michael F. Whittaker