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Two (strongly) zero-dimensional Lindel\"of topological groups whose product has positive covering dimension are constructed. An example of a Lindel\"of (strongly) zero-dimensional space whose free and free Abelian topological groups are not…

General Topology · Mathematics 2022-07-12 Ol'ga Sipacheva

We introduce dynamic asymptotic dimension, a notion of dimension for actions of discrete groups on locally compact spaces, and more generally for locally compact \'etale groupoids. We study our notion for minimal actions of the integer…

Dynamical Systems · Mathematics 2015-10-28 Erik Guentner , Rufus Willett , Guoliang Yu

For an action of a finite group on a C*-algebra, we present some conditions under which properties of the C*-algebra pass to the crossed product or the fixed point algebra. We mostly consider the ideal property, the projection property,…

Operator Algebras · Mathematics 2012-08-21 Cornel Pasnicu , N. Christopher Phillips

We introduce the completely positive rank, a notion of covering dimension for nuclear $C^*$-algebras and analyze some of its properties. The completely positive rank behaves nicely with respect to direct sums, quotients, ideals and…

Operator Algebras · Mathematics 2007-05-23 Wilhelm Winter

We review the notion of nuclear dimension for C*-algebras introduced by Winter and Zacharias. We explain why it is a non-commutative version of topological dimension. After presenting several examples, we give a brief overview of the state…

Operator Algebras · Mathematics 2020-05-28 Jorge Castillejos

We present a systematic study of the structure of crossed products and fixed point algebras by compact group actions with the Rokhlin property on not necessarily unital C*-algebras. Our main technical result is the existence of an…

Operator Algebras · Mathematics 2016-05-31 Eusebio Gardella

We show that the homoclinic C*-algebras of mixing Smale spaces are classifiable by the Elliott invariant. To obtain this result, we prove that the stable, unstable, and homoclinic C*-algebras associated to such Smale spaces have finite…

Operator Algebras · Mathematics 2017-05-10 Robin J. Deeley , Karen R. Strung

While there is only one natural dimension concept for separable, metric spaces, the theory of dimension in noncommutative topology ramifies into different important concepts. To accommodate this, we introduce the abstract notion of a…

Operator Algebras · Mathematics 2015-01-06 Hannes Thiel

Nuclear $C^*$-algebras having a system of completely positive approximations formed with convex combinations of a uniformly bounded number of order zero summands are shown to be approximately finite dimensional.

Operator Algebras · Mathematics 2020-05-28 Jorge Castillejos

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

We develop a method to bound the dynamic asymptotic dimension of isometric group actions $\Gamma\curvearrowright X$ in terms of the asymptotic dimension of a space of graphs similar to a box space of $\Gamma$ (which also determines…

Dynamical Systems · Mathematics 2021-08-03 Samantha Pilgrim

We establish four results concerning connections between actions on separable C*-algebras with Rokhlin-type properties and absorption of the Jiang-Su algebra Z. For actions of residually finite groups or of the reals which have finite…

Operator Algebras · Mathematics 2020-07-07 Ilan Hirshberg

We show that, for a given compact or discrete quantum group $G$, the class of actions of $G$ on C*-algebras is first-order axiomatizable in the logic for metric structures. As an application, we extend the notion of Rokhlin property for…

Operator Algebras · Mathematics 2018-03-06 Eusebio Gardella , Mehrdad Kalantar , Martino Lupini

We show that for any countable discrete maximally almost periodic group $G$ and any UHF algebra $A$, there exists a strongly outer product type action $\alpha$ of $G$ on $A$. We also show the existence of countable discrete almost abelian…

Operator Algebras · Mathematics 2014-09-02 Michael Y. Sun

Given a separable, AF-algebra A and an inductive limit action on A of a finitely generated abelian group with finite Rokhlin dimension with commuting towers, we give a local description of the associated crossed product C*-algebra. In…

Operator Algebras · Mathematics 2026-02-13 Sureshkumar M , Prahlad Vaidyanathan

We obtain an improved upper bound for the nuclear dimension of extensions of $\mathcal{O}_\infty$-stable $\rm{C}^*$-algebras. In particular, we prove that the nuclear dimension of a full extension of an $\mathcal{O}_\infty$-stable…

Operator Algebras · Mathematics 2021-05-12 Samuel Evington

We consider selfinjective Artin algebras whose cohomology groups are finitely generated over a central ring of cohomology operators. For such an algebra, we show that the representation dimension is strictly greater than the maximal…

Representation Theory · Mathematics 2007-11-20 Petter Andreas Bergh

The action on the trace space induced by a generic automorphism of a suitable finite classifiable C*-algebra is shown to be chaotic and weakly mixing. Model C*-algebras are constructed to observe the central limit theorem and other…

Operator Algebras · Mathematics 2023-05-08 Bhishan Jacelon

In the paper, we introduce a new concept of topological orbit dimension of $n$-tuples of elements in a unital C$^*$ algebra. Using this concept, we conclude that the Voiculescu's topological free entropy dimension of any family of…

Operator Algebras · Mathematics 2008-11-18 Don Hadwin , Qihui Li , Junhao Shen

A strongly zero-dimensional topological group containing a closed subgroup of positive covering dimension is constructed.

General Topology · Mathematics 2023-03-09 Ol'ga Sipacheva