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We show that if A is a separable, nuclear, O_infty-absorbing (or strongly purely infinite) C*-algebra, which is homotopic to zero in an ideal-system preserving way, then A is the inductive limit of C*-algebras of the form M_k(C_0(G,v)),…

Operator Algebras · Mathematics 2010-11-24 Eberhard Kirchberg , Mikael Rordam

We compute the nuclear dimension of extensions of C*-algebras involving commutative unital quotients and stable Kirchberg ideals. We identify the finite directed graphs whose C*-algebras are covered by this theorem.

Operator Algebras · Mathematics 2025-05-13 Samuel Evington , Abraham C. S. Ng , Aidan Sims , Stuart White

The residual finite-dimensionality of a $\mathrm{C}^*$-algebra is known to be encoded in a topological property of its space of representations, stating that finite-dimensional representations should be dense therein. We extend this…

Operator Algebras · Mathematics 2023-02-21 Raphaël Clouâtre , Adam Dor-On

We show that for any locally compact Hausdorff space $Y$ with finite covering dimension and for any continuous flow $\mathbb{R} \curvearrowright Y$, the resulting crossed product $C^*$-algebra $C_0(Y) \rtimes \mathbb{R}$ has finite nuclear…

Operator Algebras · Mathematics 2021-05-12 Ilan Hirshberg , Jianchao Wu

Let X be a path connected, compact metric space and let A be a unital separable simple nuclear Z-stable real rank zero C*-algebra. We classify all the unital *-embeddings (up to approximate unitary equivalence) of C(X) into A. Specifically,…

Operator Algebras · Mathematics 2007-09-11 P. W. Ng , Wilhelm Winter

In this article, we extend a well known result about real rank zero C* Algebras to higher real rank C* Algebras. The main technique used here is similar to the method in which we approximate continuous functions using projections. What we…

Operator Algebras · Mathematics 2026-04-24 Aranya Sarkar

We study uniform perturbations of intermediate C*-subalgebras of inclusions of simple C*-algebras. If a unital simple C*-algebra has a simple C*-subalgebra of finite index, then sufficiently close simple intermediate C*-subalgebras are…

Operator Algebras · Mathematics 2017-05-17 Shoji Ino , Yasuo Watatani

A classification is given of certain separable nuclear C*-algebras not necessarily of real rank zero, namely, the class of separable simple C*-algebras which are inductive limits of continuous-trace C*-algebras whose building blocks have…

Operator Algebras · Mathematics 2007-05-23 George A. Elliott , Cristian Ivanescu

We study the approximately finite-dimensional (AF) $C^*$-algebras that appear as inductive limits of sequences of finite-dimensional $C^*$-algebras and left-invertible embeddings. We show that there is such a separable AF-algebra $\mathcal…

Operator Algebras · Mathematics 2021-08-25 Saeed Ghasemi , Wiesław Kubiś

For any unital separable simple infinite-dimensional nuclear C*-algebra with finitely many extremal traces, we prove that Z-absorption, strict comparison, and property (SI) are equivalent. We also show that any unital separable simple…

Operator Algebras · Mathematics 2011-11-08 Hiroki Matui , Yasuhiko Sato

Connectivity is a homotopy invariant property of separable C*-algebras which has three notable consequences: absence of nontrivial projections, quasidiagonality and a more geometric realization of KK-theory for nuclear C*-algebras using…

Operator Algebras · Mathematics 2019-10-03 Marius Dadarlat , Ulrich Pennig

For every one-sided shift space $X$ over a finite alphabet, left special elements are those points in $X$ having at least two preimages under the shift operation. In this paper, we show that the Cuntz-Pimsner $C^*$-algebra $\mathcal{O}_X$…

Operator Algebras · Mathematics 2023-03-06 Zhuofeng He , Sihan Wei

It is shown that a separable C*-algebra is inner quasidiagonal if and only if it has a separating family of quasidiagonal irreducible representations. As a consequence, a separable C*-algebra is a strong NF algebra if and only if it is…

Operator Algebras · Mathematics 2007-12-12 Bruce Blackadar , Eberhard Kirchberg

We show that C*-algebras generated by irreducible representations of finitely generated nilpotent groups satisfy the universal coefficient theorem of Rosenberg and Schochet. This result combines with previous work to show that these…

Operator Algebras · Mathematics 2023-07-19 Caleb Eckhardt , Elizabeth Gillaspy

We obtain a characterization of the unital C*-algebras with the property that every element is a limit of products of positive elements, thereby answering a question of Murphy and Phillips.

Operator Algebras · Mathematics 2021-03-30 Leonel Robert

Let p be a polynomial in one variable. It is shown that the universal C*-algebra of the relation p(x)=0, \|x\| \le C is semiprojective, residually finite-dimensional and has trivial extension group.

Operator Algebras · Mathematics 2014-01-14 Terry Loring , Tatiana Shulman

In this article we show that the main C*-algebras describing the canonical commutation relations of quantum physics, i.e., the Weyl and resolvent algebras, are in the class of F{\o}lner C*-algebras, a class of C*-algebras admitting a kind…

Operator Algebras · Mathematics 2024-01-30 Fernando Lledó , Diego Martínez

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

It is shown that if a C*-algebra has nuclear dimension $n$ then its Cuntz semigroup has the property of $n$-comparison. It then follows from results by Ortega, Perera, and Rordam that $\sigma$-unital C*-algebras of finite nuclear dimension…

Operator Algebras · Mathematics 2010-03-09 Leonel Robert

We give an overview of the question: which positive elements in an operator algebra can be written as a linear combination of projections with positive coefficients. A special case of independent interest is the question of which positive…

Operator Algebras · Mathematics 2012-01-24 V. Kaftal , P. W. Ng , S. Zhang
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