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We show that the theory of a non-degenerate representation of a C*-algebra A over a Hilbert space H is superstable. Also, we characterize forking, orthogonality and domination of types and show that the theory has weak elimination of…

Logic · Mathematics 2012-12-03 Camilo Argoty

We show that a C*-algebra generated by an irreducible representation of a finitely generated virtually nilpotent group satisfies the universal coefficient theorem and has real rank 0. This combines with previous joint work with Gillaspy and…

Operator Algebras · Mathematics 2024-08-16 Caleb Eckhardt

A C*-algebra is called primitive if it admits a faithful and irreducible *-representation. We show that if A_1 and A_2 are separable, unital, residually finite dimensional C*-algebras that are not both two dimensional, then their unital…

Operator Algebras · Mathematics 2012-06-22 Ken Dykema , Francisco Torres-Ayala

We prove that for every $n\geq 2$, the reduced group $C^*$-algebras of the countable free groups $C^*_r(\mathbb{F}_n)$ have strict comparison. Our method works in a general setting: for $G$ in a large family of non-amenable groups,…

Operator Algebras · Mathematics 2025-08-28 Tattwamasi Amrutam , David Gao , Srivatsav Kunnawalkam Elayavalli , Gregory Patchell

We introduce the concept of finitely coloured equivalence for unital *-homomorphisms between C*-algebras, for which unitary equivalence is the 1-coloured case. We use this notion to classify *-homomorphisms from separable, unital, nuclear…

Operator Algebras · Mathematics 2019-04-24 Joan Bosa , Nathanial P. Brown , Yasuhiko Sato , Aaron Tikuisis , Stuart White , Wilhelm Winter

In this paper we analyse the structure of the Cuntz semigroup of certain $C(X)$-algebras, for compact spaces of low dimension, that have no $\mathrm{K}_1$-obstruction in their fibres in a strong sense. The techniques developed yield…

Operator Algebras · Mathematics 2011-01-26 Ramon Antoine , Francesc Perera , Luis Santiago

In this paper, we consider $\text{C}^*$-algebras with the ideal property (the ideal property unifies the simple and real rank zero cases). We define two categories related the invariants of the $\text{C}^*$-algebras with the ideal property.…

Operator Algebras · Mathematics 2017-05-30 Kun Wang

In this paper we study structural properties of the Cuntz semigroup and its functionals for continuous fields of C*-algebras over finite dimensional spaces. In a variety of cases, this leads to an answer to a conjecture posed by Blackadar…

Operator Algebras · Mathematics 2013-06-07 Ramon Antoine , Joan Bosa , Francesc Perera , Henning Petzka

We show that every AF-algebra is generated by a single operator. This was previously unclear, since the invariant that assigns to a C*-algebra its minimal number of generators lacks natural permanence properties. In particular, it may…

Operator Algebras · Mathematics 2020-11-19 Hannes Thiel

Let $p$ be a polynomial in one variable whose roots either all have multiplicity more than 1 or all have multiplicity exactly 1. It is shown that the universal $C^*$-algebra of a relation $p(x)=0$, $\|x\| \le 1$ is semiprojective. In the…

Functional Analysis · Mathematics 2011-01-21 Tatiana Shulman

We prove that a factorial tracially complete C*-algebra with CPoU has real rank zero and stable rank one. This leads to an essentially complete description of the Cuntz semigroup of these algebras. In particular, the results of this paper…

Operator Algebras · Mathematics 2026-05-11 Samuel Evington , Aaron Tikuisis

We consider three notions of divisibility in the Cuntz semigroup of a C*-algebra, and show how they reflect properties of the C*-algebra. We develop methods to construct (simple and non-simple) C*-algebras with specific divisibility…

Operator Algebras · Mathematics 2014-02-26 Leonel Robert , Mikael Rordam

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

The completely positive rank is an analogue of topological covering dimension, defined for nuclear C*-algebras via completely positive approximations. These may be thought of as simplicial approximations of the algebra, which leads to the…

Operator Algebras · Mathematics 2007-05-23 Wilhelm Winter

In this paper, we show that a completely positive linear map is weakly nuclear if and only if its complexification is weakly nuclear. It is shown that a real $C^*$-algebra is exact if and only if its complexification is exact and similar…

Operator Algebras · Mathematics 2020-05-19 Ali Ebadian , Ali Jabbari

We study bounded bilinear maps on a C$^*$-algebra $A$ having product property at $c\in A$. This leads us to the question of when a C$^*$-algebra is determined by products at $c.$ In the first part of our paper, we investigate this question…

Operator Algebras · Mathematics 2023-12-04 Jorge J. Garcés , Mykola Khrypchenko

We show that for C*-algebras with the Global Glimm Property, the rank of every operator can be realized as the rank of a soft operator, that is, an element whose hereditary sub-C*-algebra has no nonzero, unital quotients. This implies that…

Operator Algebras · Mathematics 2023-10-03 M. Ali Asadi-Vasfi , Hannes Thiel , Eduard Vilalta

We associate reduced and full C*-algebras to arbitrary rings and study the inner structure of these ring C*-algebras. As a result, we obtain conditions for them to be purely infinite and simple. We also discuss several examples.…

Operator Algebras · Mathematics 2009-06-01 Xin Li

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

We say that a C*-algebra is nowhere scattered if none of its quotients contains a minimal open projection. We characterize this property in various ways, by topological properties of the spectrum, by divisibility properties in the Cuntz…

Operator Algebras · Mathematics 2022-10-21 Hannes Thiel , Eduard Vilalta