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We investigate the interplay of the following regularity properties for non-simple C*-algebras: finite nuclear dimension, Z-stability, and algebraic regularity in the Cuntz semigroup. We show that finite nuclear dimension implies algebraic…

Operator Algebras · Mathematics 2017-04-12 Leonel Robert , Aaron Tikuisis

We demonstrate that pure C*-algebras form a robust class by proving that pureness follows from very weak comparison and divisibility properties. Using this, we show that every simple, non-elementary C*-algebra with a unique quasitrace and…

Operator Algebras · Mathematics 2024-12-18 Ramon Antoine , Francesc Perera , Hannes Thiel , Eduard Vilalta

We study strongly outer actions of discrete groups on C*-algebras in relation to (non)amenability. In contrast to related results for amenable groups, where uniqueness of strongly outer actions on the Jiang-Su algebra is expected, we show…

Operator Algebras · Mathematics 2018-03-19 Eusebio Gardella , Martino Lupini

We study comparison properties in the category Cu aiming to lift results to the C*-algebraic setting. We introduce a new comparison property and relate it to both the CFP and $\omega$-comparison. We show differences of all properties by…

Operator Algebras · Mathematics 2016-03-30 Joan Bosa , Henning Petzka

Let $X$ be an infinite compact metrizable space, and let $\sigma: X\to X$ be a minimal homeomorphism. Suppose that $(X, \sigma)$ has zero mean topological dimension. The associated C*-algebra $A=\mathrm{C}(X)\rtimes_\sigma\mathbb Z$ is…

Operator Algebras · Mathematics 2018-02-21 George A. Elliott , Zhuang Niu

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

We prove that the central sequence algebra of a separable C*-algebra is either subhomogeneous or non-exact, confirming a conjecture of Enders and Shulman. We also prove analogous dichotomy for other massive C*-algebras.

Operator Algebras · Mathematics 2023-12-01 Ilijas Farah , Ilan Hirshberg

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

Operator Algebras · Mathematics 2007-05-23 C. Ivanescu

We define a notion of tracial $\mathcal{Z}$-absorption for simple not necessarily unital C*-algebras, study it systematically, and prove its permanence properties. This extends the notion defined by Hirshberg and Orovitz for unital…

Operator Algebras · Mathematics 2022-03-25 Massoud Amini , Nasser Golestani , Saeid Jamali , N. Christopher Phillips

We introduce the notion of a computably strongly self-absorbing C*-algebra and show that the following C*-algebras are computably strongly self-absorbing: the Cuntz algebras $\mathcal{O}_2$ and $\mathcal{O}_\infty$, the UHF algebra…

Logic · Mathematics 2024-09-30 Isaac Goldbring

We prove that a unital simple approximately homogeneous (AH) C*-algebra with no dimension growth absorbs the Jiang-Su algebra tensorially without appealing to the classification theory of these algebras. Our main result continues to hold…

Operator Algebras · Mathematics 2014-02-26 Marius Dadarlat , N. Christopher Phillips , Andrew S. Toms

We give two characterizations of tracially nuclear C*-algebras. The first is that the finite summand of the second dual is hyperfinite. The second is in terms of a variant of the weak* uniqueness property. The necessary condition holds for…

Operator Algebras · Mathematics 2018-10-15 Don Hadwin , Weihua Li , Wenjing Liu , Junhao Shen

We show that a simple separable unital nuclear nonelementary $C^*$-algebra whose tracial state space has a compact extreme boundary with finite covering dimension admits uniformly tracially large order zero maps from matrix algebras into…

Operator Algebras · Mathematics 2015-08-26 Andrew Toms , Stuart White , Wilhelm Winter

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

Order unit property of a positive element in a $C^{*}$-algebra is defined. It is proved that precisely projections satisfy this order theoretic property. This way, unital hereditary $C^{*}$-subalgebras of a $C^{*}$-algebra are…

Operator Algebras · Mathematics 2007-05-23 Anil K. Karn

A pro-C^*-algebra is a (projective) limit of C^*-algebras in the category of topological *-algebras. From the perspective of non-commutative geometry, pro-C^*-algebras can be seen as non-commutative k-spaces. An element of a pro-C^*-algebra…

Category Theory · Mathematics 2011-09-27 Rachid El Harti , Gábor Lukács

We study existence of embeddings into ultrapowers of the Jiang-Su algebra $\mathcal{Z}$ and the Razak-Jacelon algebra $\mathcal{W}$. More specifically, we show that the cone over any separable $C^*$-algebra embeds into the ultrapowers of…

Operator Algebras · Mathematics 2025-06-16 Ben Bouwen , Jennifer Pi

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

When $\mathcal D$ is strongly self-absorbing we say an inclusion $B \subseteq A$ is $\mathcal D$-stable if it is isomorphic to the inclusion $B \otimes \mathcal D \subseteq A \otimes \mathcal D$. We give ultrapower characterizations and…

Operator Algebras · Mathematics 2023-06-21 Pawel Sarkowicz

We show that separable, simple, unital C*-algebras with finite decomposition rank absorb the Jiang-Su algebra Z tensorially. This has a number of consequences for Elliott's program to classify nuclear C*-algebras by their K-theory data. In…

Operator Algebras · Mathematics 2009-08-28 Wilhelm Winter