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It is shown that if $A$ and $B$ are unital separable simple nuclear $\mathcal Z$-stable C$^*$-algebras and there is a unital embedding $A \rightarrow B$ which is invertible on $KK$-theory and traces, then $A \cong B$. In particular, two…

Operator Algebras · Mathematics 2024-09-09 Christopher Schafhauser

We prove coherence of relatively quasi-free algebras over noetherian rings. Chase criterion for coherence is used.

Rings and Algebras · Mathematics 2015-01-13 Alexey Bondal , Ilya Zhdanovskiy

A heretofore longstanding open question of Kaplansky was, "Is every Type II_1 AW*-factor a von Neumann algebra?" In this paper, we answer this question in the affirmative. As a consequence, we establish that every 2-quasitrace on a unital…

Operator Algebras · Mathematics 2025-02-03 Alec Gow

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

C*-algebras are rings, sometimes nonunital, obeying certain axioms that ensure a very well-behaved representation theory upon Hilbert space. Moreover, there are some well-known features of the representation theory leading to subtle…

Operator Algebras · Mathematics 2023-07-07 Cristian Ivanescu , Dan Kucerovsky

We prolonge the list of C*-algebras for which all extensions by any stable separable C*-algebra are semi-invertible. In particular, we handle certain amalgamations, both of C*-algebras and of groups. Concerning groups we consider both…

Operator Algebras · Mathematics 2010-05-13 Vladimir Manuilov , Klaus Thomsen

We study the class of selfless C*-probability spaces introduced by Robert. It is known that a selfless tracial algebra has strict comparison and a unique trace. We prove that for separable tracial C*-algebras, selflessness is equivalent to…

Operator Algebras · Mathematics 2026-04-29 Ali Jabbari

We define E-theory for separable C*-algebras over second countable topological spaces and establish its basic properties. This includes an approximation theorem that relates the E-theory over a general space to the E-theories over finite…

K-Theory and Homology · Mathematics 2015-10-23 Marius Dadarlat , Ralf Meyer

We give a definition of hypergraph C*-algebras. These generalize the well-known graph C*-algebras as well as ultragraph C*-algebras. In contrast to those objects, hypergraph C*-algebras are not always nuclear. We provide a number of…

Operator Algebras · Mathematics 2024-05-20 Mirjam Trieb , Moritz Weber , Dean Zenner

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

Let $\Omega$ be a class of unital $\rm C^{*}$-algebras. The class of ${\rm C^*}$-algebras which are asymptotical tracially in $\Omega$, denoted by ${\rm AT}\Omega$. In this paper, we will show that the following class of ${\rm…

Operator Algebras · Mathematics 2023-10-10 Qingzhai Fan , Yutong Wu

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 find a necessary and sufficient conditions for the simplicity and uniqueness of trace for reduced free products of finite families of finite dimensional $C^*$-algebras with specified traces on them.

Operator Algebras · Mathematics 2007-05-23 Nikolay A Ivanov

In this paper, we introduce a class of non-unital tracial approximation ${\rm C^*}$-algebras. Consider the class of ${\rm C^*}$-algebras which are tracially $\mathcal{Z}$-absorbing (in the sense of Amint, Golestani, Jamali, Phillips's…

Operator Algebras · Mathematics 2022-08-30 Qingzhai Fan , Chengyu Long , Shan Zhang

A semicontinuous semifinite trace is constructed on the C*-algebra generated by the finite propagation operators acting on the L^2-sections of a hermitian vector bundle on an amenable open manifold of bounded geometry. This trace is the…

Differential Geometry · Mathematics 2007-05-23 Daniele Guido , Tommaso Isola

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

We develop a theory of type semigroups for arbitrary twisted, not necessarily Hausdorff \'etale groupoids. The type semigroup is a dynamical version of the Cuntz semigroup. We relate it to traces, ideals, pure infiniteness, and stable…

Operator Algebras · Mathematics 2025-03-28 Bartosz K. Kwaśniewski , Ralf Meyer , Akshara Prasad

We prove that the category of abstract Cuntz semigroups is bicomplete. As a consequence, the category admits products and ultraproducts. We further show that the scaled Cuntz semigroup of the (ultra)product of a family of C*-algebras agrees…

Operator Algebras · Mathematics 2020-05-27 Ramon Antoine , Francesc Perera , Hannes Thiel

We study the class of pseudocompact C*-algebras, which are the logical limits of finite-dimensional C*-algebras. The pseudocompact C*-algebras are unital, stably finite, real rank zero, stable rank one, and tracial. We show that the…

Operator Algebras · Mathematics 2016-09-26 Stephen Hardy

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