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We construct operator systems $\mathfrak C_I$ that are universal in the sense that all operator systems can be realized as their quotients. They satisfy the operator system lifting property. Without relying on the theorem by Kirchberg, we…

Operator Algebras · Mathematics 2016-12-14 Kyung Hoon Han

Kirchberg's Embedding Problem (KEP) asks whether every separable C$^*$ algebra embeds into an ultrapower of the Cuntz algebra $\mathcal{O}_2$. In this paper, we use model theory to show that this conjecture is equivalent to a local…

Operator Algebras · Mathematics 2015-03-02 Isaac Goldbring , Thomas Sinclair

In this paper, we will follow Kirchberg's categorical perspective to establish new notions of WEP and QWEP relative to a C$^*$-algebra, and develop similar properties as in the classical WEP and QWEP. Also we will show some examples of…

Operator Algebras · Mathematics 2014-10-21 Jian Liang , Sepideh Rezvani

We prove a necessary and sufficient condition for embeddability of an operator system into $\mathcal{O}_2$. Using Kirchberg's theorems on a tensor product of $\mathcal{O}_2$ and $\mathcal{O}_{\infty}$, we establish results on their operator…

Operator Algebras · Mathematics 2017-03-02 Preeti Luthra , Ajay Kumar

The Kirchberg Embedding Problem (KEP) asks if every C*-algebra embeds into an ultrapower of the Cuntz algebra $\mathcal{O}_2$. In an effort to provide a negative solution to the KEP and motivated by the recent refutation of the Connes…

Logic · Mathematics 2023-03-07 Alec Fox , Isaac Goldbring , Bradd Hart

We use representations of operator systems as quotients to deduce various characterisations of the weak expectation property (WEP) for C?*-algebras. By Kirchberg's work on WEP, these results give new formulations of Connes' embedding…

Operator Algebras · Mathematics 2013-07-04 Douglas Farenick , Ali S. Kavruk , Vern I. Paulsen , Ivan G. Todorov

Operator systems are the unital self-adjoint subspaces of the bounded operators on a Hilbert space. Complex operator systems are an important category containing the C*-algebras and von Neumann algebras, which is increasingly of interest in…

Operator Algebras · Mathematics 2025-10-07 David P. Blecher , Travis B. Russell

This note is motivated by Kirchberg's conjecture that the local lifting property (LLP) implies the lifting property (LP) for $C^*$-algebras. The author recently constructed by a "local" method an example of $C^*$-algebra with the LLP and…

Operator Algebras · Mathematics 2023-08-21 Gilles Pisier

In this paper, we employ operator system techniques to investigate structural properties of C*-algebras. In particular, we provide more direct proofs of results concerning exactness and the local lifting property (LLP) of group…

Operator Algebras · Mathematics 2025-10-30 Kenneth R. Davidson , Vern I. Paulsen , Mizanur Rahaman

We construct the first example of a $C^*$-algebra $A$ with the properties in the title. This gives a new example of non-nuclear $A$ for which there is a unique $C^*$-norm on $A \otimes A^{op}$. This example is of particular interest in…

Operator Algebras · Mathematics 2023-04-05 Gilles Pisier

An operator system modulo the kernel of a completely positive linear map of the operator system gives rise to an operator system quotient. In this paper, operator system quotients and quotient maps of certain matrix algebras are considered.…

Operator Algebras · Mathematics 2011-07-25 Douglas Farenick , Vern I. Paulsen

We show that neither the class of C*-algebras with Kirchberg's QWEP property nor the class of W*-probability spaces with the QWEP property are effectively axiomatizable (in the appropriate languages). The latter result follows from a more…

Operator Algebras · Mathematics 2023-08-29 Jananan Arulseelan , Isaac Goldbring , Bradd Hart

We establish the dual equivalence of the category of (potentially nonunital) operator systems and the category of pointed compact nc (noncommutative) convex sets, extending a result of Davidson and the first author. We then apply this dual…

Operator Algebras · Mathematics 2021-03-24 Matthew Kennedy , Se-Jin Kim , Nicholas Manor

We continue our study of tensor products in the operator system category. We define operator system quotients and exactness in this setting and refine the notion of nuclearity by studying operator systems that preserve various pairs of…

Operator Algebras · Mathematics 2010-08-19 Ali S. Kavruk , Vern I. Paulsen , Ivan G. Todorov , Mark Tomforde

The Kirchberg Embedding Problem (KEP) asks if every C*-algebra embeds into an ultrapower of the Cuntz algebra $\cal O_2$. Motivated by the recent refutation of the Connes Embedding Problem using the quantum complexity result MIP*=RE, we…

Operator Algebras · Mathematics 2023-03-03 Isaac Goldbring , Bradd Hart

Let $A$ be a unital $C^*$-algebra generated by some separable operator system $S$. More than a decade ago, Arveson conjectured that $S$ is hyperrigid in $A$ if all irreducible representations of $A$ are boundary representations for $S$.…

Operator Algebras · Mathematics 2025-10-10 Raphaël Clouâtre , Ian Thompson

A classic theorem of T. Ando characterises operators that have numerical radius at most one as operators that admit a certain positive 2x2 operator matrix completion. In this paper we consider variants of Ando's theorem, in which the…

Operator Algebras · Mathematics 2012-03-20 Douglas Farenick , Ali S. Kavruk , Vern I. Paulsen

In this article, we define operator algebras internal to a rigid C*-tensor category $\mathcal{C}$. A C*/W*-algebra object in $\mathcal{C}$ is an algebra object $\mathbf{A}$ in $\operatorname{ind}$-$\mathcal{C}$ whose category of free…

Operator Algebras · Mathematics 2017-09-13 Corey Jones , David Penneys

In this paper, we prove that if $\mathcal{A}$ is a unital separable $C^*$-algebra, $\mathcal{M}$ is a von Neumann algebra which has the Kirchberg's quotient weak expectation property (QWEP), and $\phi:\, \mathcal{A}\rightarrow \mathcal{M}$…

Operator Algebras · Mathematics 2026-01-06 Junsheng Fang , Chunlan Jiang , Liguang Wang , Yanli Wang

We introduce $p$-adic operator algebras, which are nonarchimedean analogues of $C^*$-algebras. We demonstrate that various classical examples of operator algebras - such as group(oid) $C^*$-algebras - have nonarchimedean counterparts. The…

Operator Algebras · Mathematics 2025-03-25 Alcides Buss , Luiz Felipe Garcia , Devarshi Mukherjee
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