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We obtain a description of the C*-algebras which can occur as a simple quotient of the C*-algebra of a locally injective surjection on a compact metric space of finite covering dimension.

Operator Algebras · Mathematics 2014-10-10 Toke Meier Carlsen , Klaus Thomsen

We continue our investigation, from \cite{dh}, of the ring-theoretic infiniteness properties of ultrapowers of Banach algebras, studying in this paper the notion of being purely infinite. It is well known that a $C^*$-algebra is purely…

Functional Analysis · Mathematics 2022-04-07 Matthew Daws , Bence Horváth

We show that a unital ring is generated by its commutators as an ideal if and only if there exists a natural number $N$ such that every element is a sum of $N$ products of pairs of commutators. We show that one can take $N \leq 2$ for…

Rings and Algebras · Mathematics 2024-04-04 Eusebio Gardella , Hannes Thiel

The universal C*-algebra generated by n projections has been described. As an immediate corollary one obtains structure theorem for a pair of projections and the solution to an associated index problem. This puts the study of a pair of…

Operator Algebras · Mathematics 2007-05-23 Partha Sarathi Chakraborty

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 initiate the study of the internal structure of C*-algebras associated to a left cancellative semigroup in which any two principal right ideals are either disjoint or intersect in another principal right ideal; these are variously called…

Operator Algebras · Mathematics 2017-06-20 Nathan Brownlowe , Nadia S. Larsen , Nicolai Stammeier

Given a closed ideal $I$ in a C*-algebra $A$, we develop techniques to bound the real rank of $A$ in terms of the real ranks of $I$ and $A/I$. Building on work of Brown, Lin and Zhang, we obtain complete solutions if $I$ belongs to any of…

Operator Algebras · Mathematics 2024-03-26 Hannes Thiel

We write arbitrary separable nuclear C*-algebras as limits of inductive systems of finite-dimensional C*-algebras with completely positive connecting maps. The characteristic feature of such CPC*-systems is that the maps become more and…

Operator Algebras · Mathematics 2024-10-10 Kristin Courtney , Wilhelm Winter

We study semigroup C*-algebras of $ax+b$-semigroups over integral domains. The goal is to generalize several results about C*-algebras of $ax+b$-semigroups over rings of algebraic integers. We prove results concerning K-theory and…

Operator Algebras · Mathematics 2013-06-25 Xin Li

Let $n$ be a positive integer. We introduce a concept, which we call the $n$-filling property, for an action of a group on a separable unital $C^*$-algebra $A$. If $A=C(\Omega)$ is a commutative unital $C^*$-algebra and the action is…

Operator Algebras · Mathematics 2013-02-25 P. Jolissaint , G. Robertson

We begin the systematic model theoretic study of $\mathrm{C}^*$-algebras using the tools of continuous logic.

Logic · Mathematics 2018-04-17 I. Farah , B. Hart , M. Lupini , L. Robert , A. Tikuisis , A. Vignati , W. Winter

In this paper we analyze the structure of C*-algebras associated to ultragraphs, which are generalizations of directed graphs. We characterize the simple ultragraph algebras as well as deduce necessary and sufficient conditions for an…

Operator Algebras · Mathematics 2007-05-23 Mark Tomforde

We study the ideal structure of $C^*$-algebras arising from $C^*$-correspondences. We prove that gauge-invariant ideals of our $C^*$-algebras are parameterized by certain pairs of ideals of original $C^*$-algebras. We show that our…

Operator Algebras · Mathematics 2007-05-23 Takeshi Katsura

We characterize the simplicity of universal C$^*$-algebras arising from multispinal groups. Let $\mathcal{O}_{G_{\max}}$ be the universal C$^*$-algebra associated to a multispinal group $G$. We show that the invertibility of a matrix…

Operator Algebras · Mathematics 2021-02-12 Keisuke Yoshida

We investigate the ideal structures of the C^*-algebras arising from topological graphs. We give the complete description of ideals of such C^*-algebras which are invariant under the so-called gauge action, and give the condition on…

Operator Algebras · Mathematics 2007-05-23 Takeshi Katsura

In this paper, we consider the simplicity of the C*-algebra associated to an arbitrary weakly left-resolving labeled space (E, L, E), where E is the smallest non-degenerate accommodating set. We classify all gauge-invariant ideals of C*(E,…

Operator Algebras · Mathematics 2022-04-20 EunJi Kang

The reduced C*-algebra of a countable linear group G is shown to be simple if and only if G has no nontrivial normal amenable subgroups. Moreover, these conditions are shown to be equivalent to the uniqueness of tracial state on the…

Group Theory · Mathematics 2009-05-24 Tal Poznansky

Radial representations of finitely generated free groups are studied. The associated C*-algebra is located between the reduced and full group C*-algebras and its primitive ideal space is described concretely as a topological space.

Operator Algebras · Mathematics 2025-11-26 Shigeru Yamagami

We study $C^*$-algebras arising from $C^*$-correspondences, which was introduced by the author. We prove the gauge-invariant uniqueness theorem, and obtain conditions for our $C^*$-algebras to be nuclear, exact, or satisfy the Universal…

Operator Algebras · Mathematics 2007-05-23 Takeshi Katsura

It is proved that classifiable simple separable nuclear purely infinite C*-algebras having finitely generated K-theory and torsion-free K_1 are semiprojective. This is accomplished by exhibiting these algebras as C*-algebras of infinite…

Operator Algebras · Mathematics 2007-05-23 Jack Spielberg