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Suppose that A is a C*-algebra for which A is isomorphic to A tensor Z, where Z is the Jiang-Su algebra: a unital, simple, stably finite, separable, nuclear, infinite dimensional C*-algebra with the same Elliott invariant as the complex…

Operator Algebras · Mathematics 2010-11-24 Mikael Rordam

We describe proper correspondences from graph C*-algebras to arbitrary C*-algebras by K-theoretic data. If the target C*-algebra is a graph C*-algebra as well, we may lift an isomorphism on a certain invariant to correspondences back and…

Operator Algebras · Mathematics 2025-06-25 Rasmus Bentmann , Ralf Meyer

We prove that the $L_1$-norms associated with a positive element $a$ of a unital C*-algebra are equivalent to the norm of C*-algebra if and only if $a$ is invertible.

Operator Algebras · Mathematics 2020-10-21 Andrej Novikov

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

Let $P \subset A$ be an inclusion of $\sigma$-unital C*-algebras with a finite index in the sense of Izumi. Then we introduce the Rokhlin property for a conditional expectation $E$ from $A$ onto $P$ and show that if $A$ is simple and…

Operator Algebras · Mathematics 2018-03-23 Hiroyuki Osaka , Tamotsu Teruya

We give sufficient conditions allowing one to build a C*-algebraic structure on a self-adjoint linear subspace of a C*-algebra in such a way that the subspace is naturally identified with the resulting C*-algebra via a completely positive…

Operator Algebras · Mathematics 2023-12-14 Kristin Courtney , Wilhelm Winter

We show that a $C^*$-algebra $\mathfrak{A}$ which is stably isomorphic to a unital graph $C^*$-algebra, is isomorphic to a graph $C^*$-algebra if and only if it admits an approximate unit of projections. As a consequence, a hereditary…

Operator Algebras · Mathematics 2017-02-01 Sara E. Arklint , James Gabe , Efren Ruiz

Motivated by Exel's inverse semigroup approach to combinatorial C*-algebras, in a previous work the authors defined an inverse semigroup associated with a labelled space. We construct a representation of the C*-algebra of a labelled space,…

Operator Algebras · Mathematics 2019-09-11 Giuliano Boava , Gilles G. de Castro , Fernando de L. Mortari

We prove that the C*-algebra of a second-countable, \'etale, amenable groupoid is simple if and only if the groupoid is topologically principal and minimal. We also show that if G has totally disconnected unit space, then the associated…

Operator Algebras · Mathematics 2013-10-10 Jonathan H. Brown , Lisa Orloff Clark , Cynthia Farthing , Aidan Sims

We give a complete classification of the ideals of the core of the C*-algebras associated with self-similar maps under a certain condition. Any ideal is completely determined by the intersection with the coefficient algebra C(K) of the…

Operator Algebras · Mathematics 2013-06-11 Tsuyoshi Kajiwara , Yasuo Watatani

In this article I study a number of topological and algebraic dimension type properties of simple C*-algebras and their interplay. In particular, a simple C*-algebra is defined to be (tracially) (m,\bar{m})-pure, if it has (strong tracial)…

Operator Algebras · Mathematics 2011-05-23 Wilhelm Winter

The aim of this note is to advertise a class of simple C*-algebras which includes noteworthy examples such as the Jiang-Su C*-algebra, the infinite dimensional UHF C*-algebras, the reduced group C*-algebra of the free group in infinitely…

Operator Algebras · Mathematics 2025-06-09 Leonel Robert

It has been a longstanding problem whether every amenable operator algebra is isomorphic to a (necessarily nuclear) C*-algebra. In this note, we give a nonseparable counterexample. The existence of a separable counterexample remains an open…

Operator Algebras · Mathematics 2014-03-17 Yemon Choi , Ilijas Farah , Narutaka Ozawa

We introduce two nonnegative real-valued invariants for unital and stably finite C*-algebras whose minimal instances coincide with the notion of classifiability via the Elliott invariant. The first of these is defined for AH algebras, and…

Operator Algebras · Mathematics 2007-05-23 Andrew S. Toms

We show that a not necessarily closed ideal in a C*-algebra is semiprime if and only if it is idempotent, if and only if it is closed under square roots of positive elements. Among other things, it follows that prime and semiprime ideals in…

Operator Algebras · Mathematics 2024-11-27 Eusebio Gardella , Kan Kitamura , Hannes Thiel

We study semiprojective, subhomogeneous C*-algebras and give a detailed description of their structure. In particular, we find two characterizations of semiprojectivity for subhomogeneous C*-algebras: one in terms of their primitive ideal…

Operator Algebras · Mathematics 2017-01-03 Dominic Enders

We compute the generator rank of a subhomgeneous C*-algebra in terms of the covering dimension of the pieces of its primitive ideal space corresponding to irreducible representations of a fixed dimension. We deduce that every Z-stable…

Operator Algebras · Mathematics 2022-06-14 Hannes Thiel

A C*-algebra of asymptotic fields which properly describes the infrared structure in quantum electrodynamics is proposed. The algebra is generated by the null asymptotic of electromagnetic field and the time asymptotic of charged matter…

High Energy Physics - Theory · Physics 2009-10-28 Andrzej Herdegen

A host algebra of a topological group G is a C^*-algebra whose representations are in one-to-one correspondence with certain continuous unitary representations of G. In this paper we present an approach to host algebras for infinite…

Operator Algebras · Mathematics 2007-09-10 Karl-Hermann Neeb

We construct an example of a simple nuclear separable unital stably finite Z-stable C*-algebra along with an action of the circle such that the crossed product is simple but not Z-stable.

Operator Algebras · Mathematics 2023-12-22 Ilan Hirshberg
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