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This paper explores the following regularity properties and their relationships for simple, not-necessarily-unital C*-algebras: (i) Jiang-Su stability, (ii) Unperforation in the Cuntz semigroup, and (iii) slow dimension growth (applying…

Operator Algebras · Mathematics 2012-07-18 Aaron Tikuisis

We introduce stabilised property Gamma, a C*-algebraic variant of property Gamma which is invariant under stable isomorphism. We then show that simple separable nuclear C*-algebras with stabilised property Gamma and $\mathrm{Cu}(A) \cong…

Operator Algebras · Mathematics 2021-02-02 Jorge Castillejos , Samuel Evington

We study nonunital $C^*$-algebras such that for any element there exists a local unit and prove that in such algebras there are no frames. This fact was previously known only for commutative algebras. Among other results, we establish some…

Operator Algebras · Mathematics 2025-06-17 Denis Fufaev

We give a number of equivalent conditions (including weak centrality) for a general $C^*$-algebra to have the centre-quotient property. We show that every $C^*$-algebra $A$ has a largest weakly central ideal $J_{wc}(A)$. For an ideal $I$ of…

Operator Algebras · Mathematics 2020-10-14 Robert J. Archbold , Ilja Gogić

We construct an endomorphism of the Jiang-Su algebra $\mathcal{Z}$ which does not admit a conditional expectation. This answers a question in the testamentary homework by E. Kirchberg. As an application, it is shown that any unital…

Operator Algebras · Mathematics 2024-01-30 Yasuhiko Sato

We introduce the growth rank of a C*-algebra, a (N \cup {\infty})-valued invariant which measures how far an algebra is from absorbing the Jiang-Su algebra Z tensorially. We prove that its range is exhausted by simple nuclear C*-algebras,…

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

We show that finitely generated subhomogeneous C*-algebras have finite decomposition rank. As a consequence, any separable ASH C*-algebra can be written as an inductive limit of subhomogeneous C*-algebras each of which has finite…

Operator Algebras · Mathematics 2007-05-23 Ping Wong Ng , Wilhelm Winter

We study permanence properties of the classes of stable and so-called D-stable C*-algebras, respectively. More precisely, we show that a C_0(X)-algebra A is stable if all its fibres are, provided that the underlying compact metrizable space…

Operator Algebras · Mathematics 2007-05-23 Ilan Hirshberg , Mikael Rordam , Wilhelm Winter

We introduce the notion of locally finite decomposition rank, a structural property shared by many stably finite nuclear C*-algebras. The concept is particularly relevant for Elliott's program to classify nuclear C*-algebras by K-theory…

Operator Algebras · Mathematics 2007-05-23 Wilhelm Winter

The main result here is that a simple separable C*-algebra is Z-stable (where Z denotes the Jiang-Su algebra) if (i) it has finite nuclear dimension or (ii) it is approximately subhomogeneous with slow dimension growth. This generalizes the…

Operator Algebras · Mathematics 2015-08-21 Aaron Tikuisis

Let A be a unital separable simple infinite-dimensional nuclear C*-algebra with at least one tracial state. We prove that if the trace space of A has compact finite-dimensional extreme boundary then there exist unital embeddings of matrix…

Operator Algebras · Mathematics 2012-09-14 Yasuhiko Sato

The generator problem was posed by Kadison in 1967, and it remains open until today. We provide a solution for the class of C*-algebras absorbing the Jiang-Su algebra Z tensorially. More precisely, we show that every unital, separable,…

Operator Algebras · Mathematics 2015-01-06 Hannes Thiel , Wilhelm Winter

We construct a simple C*-algebra with nuclear dimension zero that is not isomorphic to its tensor product with the Jiang-Su algebra Z, and a hyperfinite II_1 factor not isomorphic to its tensor product with the separable hyperfinite II_1…

Operator Algebras · Mathematics 2016-01-11 Ilijas Farah , Dan Hathaway , Takeshi Katsura , Aaron Tikuisis

We show that stabilizations of sufficiently noncommutative separable unital C*-algebras with finite nuclear dimension have the corona factorization property.

Operator Algebras · Mathematics 2009-04-07 Ping Wong Ng , Wilhelm Winter

We observe that a recent theorem of Sato, Toms-White-Winter and Kirchberg-Rordam also holds for certain nonunital C*-algebras. Namely, we show that an algebraically simple, separable, nuclear, nonelementary C*-algebra with strict…

Operator Algebras · Mathematics 2013-07-04 Bhishan Jacelon

We further examine the concept of uniform property Gamma for C*-algebras introduced in our joint work with Winter. In addition to obtaining characterisations in the spirit of Dixmier's work on central sequence in II$_1$ factors, we…

Operator Algebras · Mathematics 2020-09-24 Jorge Castillejos , Samuel Evington , Aaron Tikuisis , Stuart White

It is shown that every Jiang-Su stable approximately subhomogeneous C*-algebra has finite decomposition rank. Previously, it was not even known that such algebras have finite nuclear dimension. A key step in the proof is that subhomogeneous…

Operator Algebras · Mathematics 2020-03-12 George A. Elliott , Zhuang Niu , Luis Santiago , Aaron Tikuisis

An example is given of a simple, unital C*-algebra which contains an infinite and a non-zero finite projection. This C*-algebra is also an example of an infinite simple C*-algebra which is not purely infinite. A corner of this C*-algebra is…

Operator Algebras · Mathematics 2010-11-24 Mikael Rordam

We investigate how a C*-algebra could consist of functions on a noncommutative set: a discretization of a C*-algebra $A$ is a $*$-homomorphism $A \to M$ that factors through the canonical inclusion $C(X) \subseteq \ell^\infty(X)$ when…

Operator Algebras · Mathematics 2017-02-16 Chris Heunen , Manuel L. Reyes

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