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Related papers: Lifting algebraic contractions in C*-algebras

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We show that a C*-algebra with topological dimension zero has the Global Glimm Property (every hereditary subalgebra contains an almost full nilpotent element) if and only if it is nowhere scattered (no hereditary subalgebra admits a…

Operator Algebras · Mathematics 2025-09-05 Ping Wong Ng , Hannes Thiel , Eduard Vilalta

We show that, when $A$ is a separable C*-algebra, every countably generated Hilbert $A$-module is projective (with bounded module maps as morphisms). We also study the approximate extensions of bounded module maps. In the case that $A$ is a…

Operator Algebras · Mathematics 2023-01-12 Lawrence G. Brown , Huaxin Lin

Let E be a row-finite directed graph. We prove that there exists a C*-algebra C*_{min}(E) with the following co-universal property: given any C*-algebra B generated by a Toeplitz-Cuntz-Krieger E-family in which all the vertex projections…

Operator Algebras · Mathematics 2008-09-16 Aidan Sims

We study the elementary C*-algebra whose elements are the sum of a diagonal plus a compact operator. We describe the structure of the unitary group, the sets of ideals, automorhisms and projections.

Operator Algebras · Mathematics 2019-03-15 Esteban Andruchow , Eduardo Chiumiento , Alejandro Varela

We extend known results about commutative $C^*$-algebras generated Toeplitz operators over the unit ball to the supermanifold setup. This is obtained by constructing commutative $C^*$-algebras of super Toeplitz operators over the super ball…

Operator Algebras · Mathematics 2015-08-21 R. Quiroga-Barranco , A. Sánchez-Nungaray

We prove that every unital stably finite simple amenable $C^*$-algebra $A$ with finite nuclear dimension and with UCT such that every trace is quasi-diagonal has the property that $A\otimes Q$ has generalized tracial rank at most one, where…

Operator Algebras · Mathematics 2023-02-16 George A. Elliott , Guihua Gong , Huaxin Lin , Zhuang Niu

We investigate when discrete, amenable groups have $C^*$-algebras of real rank zero. While it is known that this happens when the group is locally finite, the converse in an open problem. We show that if $C^*(G)$ has real rank zero, then…

Operator Algebras · Mathematics 2023-10-03 Iason Moutzouris

We regard a right Hilbert C*-module X over a C*-algebra A endowed with an isometric *-homomorphism \phi: A\to L_A(X) as an object X_A of the C*-category of right Hilbert A-modules. Following a construction by the first author and Roberts,…

funct-an · Mathematics 2008-02-03 Sergio Doplicher , Claudia Pinzari , Rita Zuccante

A $C^*$-algebra $A$ is said to have the homotopy lifting property if for all $C^*$-algebras $B$ and $E$, for every surjective $^*$-homomorphism $\pi \colon E \rightarrow B$ and for every $^*$-homomorphism $\phi \colon A \rightarrow E$, any…

Operator Algebras · Mathematics 2024-03-27 José R. Carrión , Christopher Schafhauser

We present a new method of analysis of associative algebras. This method bears a certain resemblance to the famous analysis of commutative $C^*$-algebras in which an important role is played by multiplicative functionals over the algebra.…

Rings and Algebras · Mathematics 2007-05-23 Vladimir Dergachev

Let $0\longrightarrow \B\stackrel{j}{\longrightarrow}E\stackrel{\pi}{\longrightarrow}\A\longrightarrow 0$ be an extension of $\A$ by $\B$, where $\A$ is a unital simple purely infinite $C^{*}$--algebra. When $\B$ is a simple separable…

Operator Algebras · Mathematics 2010-07-01 Zhihua Li , Yifeng Xue

We introduce the decomposition rank, a notion of covering dimension for nuclear C^*-algebras. The decomposition rank generalizes ordinary covering dimension and has nice permanence properties; in particular, it behaves well with respect to…

Operator Algebras · Mathematics 2007-05-23 Eberhard Kirchberg , Wilhelm Winter

Let $A$ be a $C^*$-algebra. It is shown that the following conditions are equinvalent: (1) $A$ is scattered, (2) every $C^*$-subalgebra of $A$ is AF, (3) every $C^*$-subalgebra of $A$ has real rank zero.

Operator Algebras · Mathematics 2010-08-24 Kusuda , M

We characterize the class of RFD $C^*$-algebras as those containing a dense subset of elements that attain their norm under a finite-dimensional representation. We show further that this subset is the whole space precisely when every…

Operator Algebras · Mathematics 2017-07-10 Kristin Courtney , Tatiana Shulman

Given a closed ideal $I$ in a C*-algebra $A$, we show that $A$ is pure if and only if $I$ and $A/I$ are pure. More generally, we study permanence of comparison and divisibility properties when passing to extensions. As an application we…

Operator Algebras · Mathematics 2025-06-13 Francesc Perera , Hannes Thiel , Eduard Vilalta

The well-behaved representations of the coordinate algebra of a 2-dimensional quantum complex plane are classified and a C*-algebra is defined which can be viewed as the algebra of continuous functions on the 2-dimensional quantum complex…

Quantum Algebra · Mathematics 2018-02-20 Ismael Cohen , Elmar Wagner

Let $\mathcal{A}$ be a separable nuclear C*-algebra, and $\mathcal{B}$ be a nonunital separable simple $\mathcal{Z}$-stable C*-algebra. Continuing the work from Gabe-Lin-Ng, we classify all essential extensions, with large complement, of…

Operator Algebras · Mathematics 2026-02-25 Ping Wong Ng , Cangyuan Wang

In this paper we give an example of a proper standard C*-algebra (a proper C*-subalgebra of B(H) containing C(H)) whose automorphism and isometry groups are topologically reflexive. Furthermore, we prove that in the case of extensions of…

Functional Analysis · Mathematics 2008-02-03 Lajos Molnar

We show that the spectrum X of a weakly semiprojective, commutative C*-algebra C(X) is at most one dimensional. This completes the work of S{\o}rensen and Thiel on the characterization of weak (semi-)projectivity for commutative…

Operator Algebras · Mathematics 2011-02-17 Dominic Enders

We revisit the notion of tracial approximation for unital simple C*-algebras. We show that a unital simple separable C*-algebra A is asymptotically tracially in the class of C*-algebras with finite nuclear dimension if and only if A is…

Operator Algebras · Mathematics 2020-04-24 Xuanlong Fu , Huaxin Lin