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Related papers: Characterizations of ordered operator spaces

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We establish operator-valued versions of the earlier foundational factorization results for noncommutative polynomials due to Helton (Ann.~Math., 2002) and one of the authors (Linear Alg.~Appl., 2001). Specifically, we show that every…

Functional Analysis · Mathematics 2026-01-13 Abhay Jindal , Igor Klep , Scott McCullough

We give necessary and sufficient conditions for a bounded operator defined between complex Hilbert spaces to be absolutely norm attaining. We discuss structure of such operators in the case of self-adjoint and normal operators separately.…

Spectral Theory · Mathematics 2018-01-09 G. Ramesh , D. Venku Naidu

We investigate the category of ``matricial order operator spaces,'' which generalize operator systems, being equipped with both matricial norms and matricial order. For these objects, we develop duality theory. Taking a cue from the theory…

Functional Analysis · Mathematics 2026-05-22 Roy Araiza , Timur Oikhberg

We introduce three metrics on the set of quantum probability measures over a compact Hausdorff space and characterize them in terms of the completely bounded norm of the corresponding unital completely positive maps. We extend the existing…

Operator Algebras · Mathematics 2024-09-26 Georgios Baziotis

We study an operator norm localization property and its applications to the coarse Novikov conjecture in operator K-theory. A metric space X is said to have operator norm localization property if there exists a positive number c such that…

Metric Geometry · Mathematics 2007-11-15 Xiaoman Chen , Romain Tessera , Xianjin Wang , Guoliang Yu

Let $(E,\mathcal E,\mu)$ be a measure space and $G\colon E\times E\to [0,\infty]$ be measurable. Moreover, let $\mathcal F\!_{ui}$ denote the set of all $q\in\mathcal E^+$ (measurable numerical functions $q\ge 0$ on $E$) such that…

Functional Analysis · Mathematics 2022-01-25 Wolfhard Hansen

Let $X$ be a (real or complex) rearrangement-in\-va\-riant function space on $\Om$ (where $\Om = [0,1]$ or $\Om \subseteq \bbN$) whose norm is not proportional to the $L_2$-norm. Let $H$ be a separable Hilbert space. We characterize…

Functional Analysis · Mathematics 2016-09-06 Beata Randrianantoanina

We investigate $\rho$-orthogonality and its local symmetry in the space of bounded linear operators. A characterization of Hilbert space operators with symmetric numerical range is established in terms of $\rho$-orthogonality. Further, we…

Functional Analysis · Mathematics 2025-12-15 Souvik Ghosh , Kallol Paul , Debmalya Sain

The difficulty for solving ill-posed linear operator equations in Hilbert space is reflected by the strength of ill-posedness of the governing operator, and the inherent solution smoothness. In this study we focus on the ill-posedness of…

Numerical Analysis · Mathematics 2025-01-24 Peter Mathé , Bernd Hofmann

In this note we study the generalized Hilbert series operator $H_{\mu}$, induced by a positive Bore measure $\mu$ on $[0, 1)$, between weighted sequence spaces. We characterize the measures $\mu$ for which $H_{\mu}$ is bounded between…

Classical Analysis and ODEs · Mathematics 2022-05-12 Jianjun Jin , Shuan Tang

We obtain a necessary and sufficient condition for a weighted composition operator to be co-isometric on a general weighted Hardy space of analytic functions in the unit disk whose reproducing kernel has the usual natural form. This turns…

Complex Variables · Mathematics 2021-07-14 María J. Martín , Alejandro Mas , Dragan Vukotić

In this paper, we consider representations induced by general positive and completely positive sesquilinear maps with values in ordered Banach bimodules, such as the space of trace-class operators and the spaces of bounded linear operators…

Functional Analysis · Mathematics 2026-02-13 Giorgia Bellomonte , Stefan Ivkovic , Camillo Trapani

The matrix normed structure of the unitization of a (non-selfadjoint) operator algebra is determined by that of the original operator algebra. This yields a classification up to completely isometric isomorphism of two-dimensional unital…

funct-an · Mathematics 2007-05-23 Ralf Meyer

In this note, we define a bounded variant on the Hilbert projective metric on an infinite dimensional space $E$ and study the contraction properties of the projective maps associated with positive linear operators on $E$. More precisely, we…

Functional Analysis · Mathematics 2025-02-07 Maxime Ligonnière

This paper studies the behaviour of iterates of weighted composition operators acting on spaces of analytic functions, with particular emphasis on the Hardy space $H^2$. Questions relating to uniform, strong and weak convergence are…

Functional Analysis · Mathematics 2020-02-11 I. Chalendar , J. R. Partington

In this paper we consider the operator system $\cl{S}_n$ generated by $n$ Cuntz isometries, i.e. the span of the generators of the Cuntz algebra $\cl{O}_n$ together with their adjoints and the identity. We define an operator subsystem…

Operator Algebras · Mathematics 2015-04-14 Da Zheng

A necessary and sufficient condition for an operator space to support a multiplication making it completely isometric and isomorphic to a unital operator algebra is proved. The condition involves only the holomorphic structure of the Banach…

Operator Algebras · Mathematics 2015-12-11 Matthew Neal , Bernard Russo

This is a companion to recent papers of the authors; here we construct the `noncommutative Shilov boundary' of a (possibly nonunital) selfadjoint ordered space of Hilbert space operators. The morphisms in the universal property of the…

Operator Algebras · Mathematics 2007-05-23 David P. Blecher , Kay Kirkpatrick , Matthew Neal , Wend Werner

Schur-Horn theorems focus on determining the diagonal sequences obtainable for an operator under all possible basis changes, formally described as the range of the canonical conditional expectation of its unitary orbit. Following a brief…

Functional Analysis · Mathematics 2015-10-05 Jireh Loreaux , Gary Weiss

Let $H$ be a complex separable Hilbert space and $B(H)$ the algebra of all bounded linear operators on $H$. In this paper, we give considerable generalizations of the inequalities for norms of commutators of normal operators. Let $S, T \in…

Functional Analysis · Mathematics 2019-03-26 N. B. Okelo , P. O. Mogotu