English
Related papers

Related papers: Nonseparable UHF algebras I: Dixmier's problem

200 papers

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

In this paper, we study the notion of a separability idempotent in the C*-algebra framework. This is analogous to the notion in the purely algebraic setting, typically considered in the case of (finite-dimensional) algebras with identity,…

Quantum Algebra · Mathematics 2017-09-26 Byung-Jay Kahng , Alfons Van Daele

Glimm's theorem says that a UHF algebra is almost embedded in a separable $C^*$-algebra not of type I. Applying his methods we obtain a covariant version of his result; a UHF algebra with a product type automorphism is covariantly embedded…

Operator Algebras · Mathematics 2013-03-28 Akira Noguchi

Let $X$ be a finite dimensional compact metrizable space. We study a technique which employs semiprojectivity as a tool to produce approximations of $C(X)$-algebras by $C(X)$-subalgebras with controlled complexity. The following…

Operator Algebras · Mathematics 2009-07-17 Marius Dadarlat

Examples of (strongly continuous) one-parameter groups of automorphisms of UHF C*-algebras are given. One example has the property that the infinitesimal generator does not have a union of finite-dimensional subalgebras as a core. (This…

Operator Algebras · Mathematics 2009-10-31 Akitaka Kishimoto

We provide some background on the category of classifiable $\mathrm{C}^*$-algebras, whose objects are infinite-dimensional, simple, separable, unital $\mathrm{C}^*$-algebras that have finite nuclear dimension and satisfy the universal…

Operator Algebras · Mathematics 2025-12-09 Bhishan Jacelon

We give two characterizations of tracially nuclear C*-algebras. The first is that the finite summand of the second dual is hyperfinite. The second is in terms of a variant of the weak* uniqueness property. The necessary condition holds for…

Operator Algebras · Mathematics 2018-10-15 Don Hadwin , Weihua Li , Wenjing Liu , Junhao Shen

We give a classification result for a certain class of $C^{*}$-algebras $\mathfrak{A}$ over a finite topological space $X$ in which there exists an open set $U$ of $X$ such that $U$ separates the finite and infinite subquotients of…

Operator Algebras · Mathematics 2015-05-28 Soren Eilers , Gunnar Restorff , Efren Ruiz

We extend in this paper the characterisation of a separable nuclear \cst-algebra given by Kirchberg proving that given a unital separable continuous field of nuclear C*-algebras A over a compact metrizable space X, the C(X)-algebra A is…

Operator Algebras · Mathematics 2016-09-07 Etienne Blanchard

We prove that the central sequence algebra of a separable C*-algebra is either subhomogeneous or non-exact, confirming a conjecture of Enders and Shulman. We also prove analogous dichotomy for other massive C*-algebras.

Operator Algebras · Mathematics 2023-12-01 Ilijas Farah , Ilan Hirshberg

We discuss the existence of (injectively) universal C*-algebras and prove that all C*-algebras of density character $\aleph_1$ embed into the Calkin algebra, $Q(H)$. Together with other results, this shows that each of the following…

Operator Algebras · Mathematics 2018-10-17 Ilijas Farah , Ilan Hirshberg , Alessandro Vignati

We construct uncountably many mutually nonisomorphic simple separable stably finite unital exact C$^\ast$-algebras which are not isomorphic to their opposite algebras. In particular, we prove that there are uncountably many possibilities…

Operator Algebras · Mathematics 2024-02-14 N. Christopher Phillips , Maria Grazia Viola

It is shown that a separable exact residually finite dimensional C*-algebra with locally finitely generated (rational) even K-homology embeds in a uniformly hyperfinite C*-algebra.

Operator Algebras · Mathematics 2018-07-10 Marius Dadarlat

A C*-algebra is n-homogeneous (where n is finite) if every its nonzero irreducible representation acts on an n-dimensional Hilbert space. An elementary proof of Fell's characterization of n-homogeneous C*-algebras (by means of their…

Operator Algebras · Mathematics 2017-05-26 Piotr Niemiec

It is shown that a C*-algebra of the form C(X,U), where U is a UHF algebra, is not an inductive limit of subhomogeneous C*-algebras of topological dimension less than that of X. This is in sharp contrast to dimension-reduction phenomenon in…

Operator Algebras · Mathematics 2015-08-21 Aaron Tikuisis

We show that every separable simple tracially approximately divisible $C^*$-algebra has strict comparison, is either purely infinite, or has stable rank one. As a consequence, we show that every (non-unital) finite simple ${\cal Z}$-stable…

Operator Algebras · Mathematics 2021-09-07 Xuanlong Fu , Kang Li , Huaxin Lin

In the paper, we give two new characterizations of separable inner quasidiagonal C*-algebras. Base on these characterizations, we show that a unital full free product of two inner quasidiagonal C*-algebras is inner quasidiagonal again. As…

Operator Algebras · Mathematics 2015-04-21 Qihui Li

Given an arbitrary countable ordinal $\alpha $, we introduce the notion of type $I_{\alpha }$ C*-algebra and $\alpha $-subhomogeneous C*-algebra. When $\alpha =0$, these recover the notions of Fell C*-algebra and of commutative C*-algebra,…

Operator Algebras · Mathematics 2026-02-24 Martino Lupini

It has been a longstanding problem whether every amenable operator algebra is isomorphic to a (necessarily nuclear) C*-algebra. In this note, we give a nonseparable counterexample. The existence of a separable counterexample remains an open…

Operator Algebras · Mathematics 2014-03-17 Yemon Choi , Ilijas Farah , Narutaka Ozawa

A well-known result in dynamical systems asserts that any Cantor minimal system $(X,T)$ has a maximal rational equicontinuous factor $(Y,S)$ which is in fact an odometer, and realizes the rational subgroup of the $K_0$-group of $(X,T)$,…

Operator Algebras · Mathematics 2024-07-25 Nasser Golestani , Saeid Maleki Oche