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In the given article the notion of infinite norm decomposition of a C$^*$-algebra is investigated. The norm decomposition is some generalization of Peirce decomposition. It is proved that the infinite norm decomposition of any C$^*$-algebra…

Operator Algebras · Mathematics 2010-08-03 Farkhad Arzikulov

In this paper, we investigate the general properties and structure of $C^*$-extreme points within the $C^*$-convex set $\mathrm{UCP}(\mathcal{A},B(\mathcal{H}))$ of all unital completely positive (UCP) maps from a unital real $C^*$-algebra…

Operator Algebras · Mathematics 2025-09-30 Anand O. R , K. Sumesh , Arindam Sutradhar

Suppose $\mathcal{A}$ is a separable unital ASH C*-algebra, $\mathcal{R}$ is a sigma-finite II$_{\infty}$ factor von Neumann algebra, and $\pi,\rho :\mathcal{A}\rightarrow\mathcal{R}$ are unital $\ast$-homomorphisms such that, for every…

Operator Algebras · Mathematics 2020-08-18 Qihui Li , Don Hadwin , Wenjing Liu

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 define an admissible decomposition of a graph $E$ into subgraphs $F_1$ and $F_2$, and consider the intersection graph $F_1\cap F_2$ as a subgraph of both $F_1$ and $F_2$. We prove that, if the graph $E$ is row finite and its…

Operator Algebras · Mathematics 2019-06-04 Piotr M. Hajac , Sarah Reznikoff , Mariusz Tobolski

In this paper we give characterizations of essential left ideals of a C*-algebra $A$ in terms of their properties as operator $A$-modules. Conversely, we seek C*-algebraic characterizations of those ideals $J$ in $A$ such that $A$ is an…

Operator Algebras · Mathematics 2007-05-23 Masayoshi Kaneda , Vern Ival Paulsen

In this paper, we discuss the associated family of harmonic maps $\mathcal{F}: M \rightarrow G/K$ from a Riemann surface $M$ into inner symmetric spaces of compact or non-compact type which are either algebraic or totally symmetric. These…

Differential Geometry · Mathematics 2024-08-23 Josef F. Dorfmeister , Peng Wang

Let $F$ be an algebraically closed field and consider the Lie algebra ${\mathfrak g}=\langle x\rangle\ltimes {\mathfrak a}$, where $\mathrm{ad}\, x$ acts diagonalizably on the abelian Lie algebra ${\mathfrak a}$. Refer to a ${\mathfrak…

Representation Theory · Mathematics 2014-08-12 Leandro Cagliero , Fernando Szechtman

Both completely positive and completely copositive maps stay decomposable under tensor powers, i.e under tensoring the linear map with itself. But are there other examples of maps with this property? We show that this is not the case: Any…

Quantum Physics · Physics 2019-01-17 Alexander Müller-Hermes

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

This paper contains a quite detailed description of the C*-algebra arising from the transformation groupoid of a rational map of degree at least two on the Riemann sphere. The algebra is decomposed stepwise via extensions of familiar…

Operator Algebras · Mathematics 2012-02-14 Klaus Thomsen

We prove a number of results having to do with equipping type-I $\mathrm{C}^*$-algebras with compact quantum group structures, the two main ones being that such a compact quantum group is necessarily co-amenable, and that if the…

Operator Algebras · Mathematics 2020-08-11 Alexandru Chirvasitu , Jacek Krajczok , Piotr M. Sołtan

A Banach involutive algebra is called a Krein C*-algebra if there is a fundamental symmetry (an involutive automorphism of period 2) such that the C*-property is satisfied when the original involution is replaced with the new one obtained…

Operator Algebras · Mathematics 2014-09-05 Pichkitti Bannangkoon , Paolo Bertozzini , Wicharn Lewkeeratiyutkul

We describe absolutely ordered $p$-normed spaces, for $1 \le p \le \infty$ which presents a model for "non-commutative" vector lattices and includes order theoretic orthogonality. To demonstrate its relevance, we introduce the notion of…

Functional Analysis · Mathematics 2017-12-19 Anil Kumar Karn

For every finite dimensional Lie supergroup $(G,\mathfrak g)$, we define a $C^*$-algebra $\mathcal A:=\mathcal A(G,\mathfrak g)$, and show that there exists a canonical bijective correspondence between unitary representations of…

Representation Theory · Mathematics 2016-03-09 Karl-Hermann Neeb , Hadi Salmasian

Let $A$ be a unital Banach algebra. We give a characterization of the left Banach $A$-modules $X$ for which there exists a commutative unital $C^*$-algebra $C(K)$, a linear isometry $i\colon X\to C(K)$, and a contractive unital homomorphism…

Operator Algebras · Mathematics 2007-05-23 David P. Blecher , Christian Le Merdy

We prove that a discrete group $G$ is amenable iff it is strongly unitarizable in the following sense: every unitarizable representation $\pi$ on $G$ can be unitarized by an invertible chosen in the von Neumann algebra generated by the…

Operator Algebras · Mathematics 2014-12-23 Gilles Pisier

This paper brings together C*-algebras and algebraic topology in terms of viewing a C*-algebraic invariant in terms of a topological spectrum. E-theory, E(A,B), is a bivariant functor in the sense that is a cohomology functor in the first…

Operator Algebras · Mathematics 2017-08-11 Sarah L. Browne

Let A be a unital C*-algebra. We shall introduce involutive A-A-equivalence bimodules and prove that any C*-algebra containing A with Watatani index 2 is constructed by an involutive A-A-equivalence bimodule.

Operator Algebras · Mathematics 2007-05-23 K. Kodaka , T. Teruya

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