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Related papers: Axiomatic theory for C*-algebras

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In the present paper we study the structure of C*-$algebras generated by a certain *-algebra A and a partial isometry inducing an endomorphism of A.

Operator Algebras · Mathematics 2007-05-23 A. Lebedev , A. Odzijewicz

We compute the genus of a rational quadratic form in terms of the K-theory of a C*-algebra attached to the adelic orthogonal group of the form. As a corollary, one gets a higher composition law for the rational quadratic forms. As an…

Number Theory · Mathematics 2019-10-09 Igor Nikolaev

We extend the family of classical Schur algebras in type A, which determine the polynomial representation theory of general linear groups over an infinite field, to a larger family, the rational Schur algebras, which determine the rational…

Representation Theory · Mathematics 2007-11-17 Richard Dipper , Stephen Doty

In this paper we introduce a new formalism for $K$-theory, called squares $K$-theory. This formalism allows us to simultaneously generalize the usual three-term relation $[B] = [A] + [C]$ for an exact sequence $A \hookrightarrow B…

K-Theory and Homology · Mathematics 2026-02-11 Jonathan Campbell , Josefien Kuijper , Mona Merling , Inna Zakharevich

We show that if $G$ is a second countable locally compact Hausdorff \'etale groupoid carrying a suitable cocycle $c:G\to\mathbb{Z}$, then the reduced $C^*$-algebra of $G$ can be realised naturally as the Cuntz-Pimsner algebra of a…

Operator Algebras · Mathematics 2018-04-19 Adam Rennie , David Robertson , Aidan Sims

We introduce and investigate some examples of C$^*$-algebras which are related to multiplication maps in the ring of $p$-adic integers. We find ideals within these algebras and use the corresponding short exact sequences to compute the…

Operator Algebras · Mathematics 2023-12-18 Shelley Hebert , Slawomir Klimek , Matt McBride , J. Wilson Peoples

For a completely Hausdorff quasi-topological group $G$, we construct a universal pro-$C^*$-algebra $C(E^+G)$ as the non-commutative geometer's analogue of the total space $EG$ of the classifying principal $G$-bundle $EG\to BG$. The…

Operator Algebras · Mathematics 2023-05-01 Alexandru Chirvasitu , Mariusz Tobolski

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 develop a general framework to deal with the unitary representations of quantum groups using the language of C*-algebras. Using this framework, we prove that the duality holds in a general context. This extends the framework of the…

Quantum Algebra · Mathematics 2007-05-23 T. Masuda , Y. Nakagami , S. L. Woronowicz

We define N-theory being some analogue of K-theory on the category of von Neumann algebras such that $K_0(A)\subset N_0(A)$ for any von Neumann algebra A. Moreover, it turns out to be possible to construct the extension of the Chern…

Operator Algebras · Mathematics 2007-05-23 A. A. Pavlov

We prove that the category of abstract Cuntz semigroups is bicomplete. As a consequence, the category admits products and ultraproducts. We further show that the scaled Cuntz semigroup of the (ultra)product of a family of C*-algebras agrees…

Operator Algebras · Mathematics 2020-05-27 Ramon Antoine , Francesc Perera , Hannes Thiel

We study the E-theory group $E_{[0,1]}(A,B)$ for a class of C*-algebras over the unit interval with finitely many singular points, called elementary $C[0,1]$-algebras. We use results on E-theory over non-Hausdorff spaces to describe…

Operator Algebras · Mathematics 2013-12-17 M. Dadarlat , P. Vaidyanathan

In this memoir we develop a framework to study rigidity problems for Roe-like C*-algebras of countably generated coarse spaces. The main goal is to give a complete and self-contained solution to the problem of C*-rigidity for proper…

Operator Algebras · Mathematics 2025-03-11 Diego Martínez , Federico Vigolo

We prove that the Cuntz-Pimsner algebra O(E) of a vector bundle E over a compact metrizable space X is determined up to an isomorphism of C(X)-algebras by the ideal (1-[E])K(X) of the K-theory ring K(X). Moreover, if E and F are vector…

Operator Algebras · Mathematics 2010-04-27 Marius Dadarlat

We review the notions of a multiplier category and the $W^{*}$-envelope of a $C^{*}$-category. We then consider the notion of an orthogonal sum of a (possibly infinite) family of objects in a $C^{*}$-category. Furthermore, we construct…

K-Theory and Homology · Mathematics 2025-12-11 Ulrich Bunke , Alexander Engel

We show that the C*-algebra of a row-finite source-free k-graph is Rieffel-Morita equivalent to a crossed product of an AF algebra by the fundamental group of the k-graph. When the k-graph embeds in its fundamental groupoid, this AF algebra…

Operator Algebras · Mathematics 2024-03-05 Nathan Brownlowe , Alex Kumjian , David Pask , Aidan Sims

Let $\Lambda = \mathbb{Z}^n$ with lexicographic ordering. $\Lambda$ is a totally ordered group. Let $X = \Lambda^+ * \Lambda^+$. Then $X$ is a $\Lambda$-tree. Analogous to the construction of graph $C^*$-algebras, we form a groupoid whose…

Operator Algebras · Mathematics 2011-01-31 Menassie Ephrem

We provide a construction of Roe (C*-)algebras of general coarse spaces in terms of coarse geometric modules. This extends the classical theory of Roe algebras of metric spaces and gives a unified framework to deal with either uniform or…

Operator Algebras · Mathematics 2024-04-03 Diego Martínez , Federico Vigolo

We show that every strongly $\mathbb{Z}$-graded C*-algebra (equivalently, every C*-algebra carrying a strongly continuous $\mathbb{T}$-action with full spectral subspaces) is a Cuntz--Pimsner algebra, and describe subalgebras and subspaces…

Operator Algebras · Mathematics 2025-07-08 Efren Ruiz , Aidan Sims

In previous definition of $\mathrm{E}$-theory, separability of the $\mathrm{C}^*$-algebras is needed either to construct the composition product or to prove the long exact sequences. Considering the latter, the potential failure of the long…

Operator Algebras · Mathematics 2022-12-15 Christopher Wulff