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We define a p-norm in the context of quantum random variables, measurable operator-valued functions with respect to a positive operator-valued measure. This norm leads to a operator-valued L^p space that is shown to be complete. Various…

Functional Analysis · Mathematics 2021-08-31 Christopher Ramsey , Adam Reeves

An absolute continuity approach to quasinormality which relates the operator in question to the spectral measure of its modulus is developed. Algebraic characterizations of some classes of operators that emerged in this context are…

Functional Analysis · Mathematics 2013-10-15 Zenon Jan Jablonski , Il Bong Jung , Jan Stochel

We investigate the $n$th root problem for bounded operators on a Hilbert space within the class of conditionally positive definite (CPD) operators determined by the L\'evy--Khintchine formula. The class contains subnormal operators,…

Functional Analysis · Mathematics 2026-04-14 Zenon Jan Jabłoński , Il Bong Jung , Paweł Pietrzycki , Jan Stochel

We establish that the complete theory of a Hilbert space equipped with a normal operator has the Schr\"oder-Bernstein property. This answers a question of Argoty, Berenstein, and the first-named author. We also prove an analogous statement…

Logic · Mathematics 2025-08-18 Nicolás Cuervo Ovalle , Isaac Goldbring , Netanel Levi

Truncated Toeplitz operators and their asymmetric versions are studied in the context of the Hardy space $H^p$ of the half-plane for $1<p<\infty$. It is shown that they are equivalent after extension to $2 \times 2$ matricial Toeplitz…

Functional Analysis · Mathematics 2015-04-27 M. Cristina Câmara , Jonathan R. Partington

Composition operators with analytic symbols on some reproducing kernel Hilbert spaces of entire functions on a complex Hilbert space are studied. The questions of their boundedness, seminormality and positivity are investigated. It is…

Functional Analysis · Mathematics 2016-10-17 Jan Stochel , Jerzy B. Stochel

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 natural duality between "topological" and "regular," both considered as convergence space properties, extends naturally to p-regular convergence spaces, resulting in the new concept of a p-topological convergence space. Taking advantage…

General Topology · Mathematics 2007-05-23 Scott A. Wilde , D. C. Kent

We prove that operators satisfying the hypotheses of the extrapolation theorem for Muckenhoupt weights are bounded on weighted Morrey spaces. As a consequence, we obtain at once a number of results that have been proved individually for…

Functional Analysis · Mathematics 2017-10-23 Javier Duoandikoetxea , Marcel Rosenthal

In this paper, we introduce a new semi-norm of operators on a semi-Hilbertian space, which generalizes the A-numerical radius and A-operator semi-norm. We study the basic properties of this semi-norm, including upper and lower bounds for…

Functional Analysis · Mathematics 2024-08-14 Pintu Bhunia , Anirban Sen , Kallol Paul

Let $T$ be an absolutely continuous polynomially bounded operator, and let $\theta$ be a singular inner function. It is shown that if $\theta(T)$ is invertible and some additional conditions are fulfilled, then $T$ has nontrivial…

Functional Analysis · Mathematics 2019-12-17 Maria F. Gamal'

In this paper, boundedness of Hausdorff operator on weak central Morrey space is obtained. Furthermore, we investigate the weak bounds of p- adic fractional Hausdorff Operator on weighted p-adic weak Lebesgue Space. We also obtain the…

Functional Analysis · Mathematics 2019-11-22 Naqash Sarfraz , Ferit Gurbuz

In this paper, we establish the essential criteria for the hyponormality and quasinormality of the unbounded Toeplitz operator $T_{\varphi}$ with non-harmonic symbol, acting on the Fock-Sobolev space $F^{2, m}(\mathbb{C})$. The study shows…

Functional Analysis · Mathematics 2025-12-02 Anuradha Gupta , Kajal Negi

We present some properties of orthogonality and relate them with support disjoint and norm inequalities in p Schatten ideals. In addition, we investigate the problem of characterization of norm parallelism for bounded linear operators. We…

Functional Analysis · Mathematics 2021-07-23 T. Bottazzi , C. Conde , M. S. Moslehian , P. Wojcik , A. Zamani

In this paper, we estimate an operator norm of dilation operators on block spaces ($\mathfrak{B}_{r,\alpha}(\mathbb{Q}_p)$) over $p$-adic field. With this estimate, we establish the boundedness of $p$-adic Hardy-Hilbert type integral…

Functional Analysis · Mathematics 2023-03-22 Salman Ashraf

We prove that for operators satistying weighted inequalities with $A_p$ weights the boundedness on a certain class of Morrey spaces holds with weights of the form $|x|^\alpha w(x)$ for $w\in A_p$. In the case of power weights the shift with…

Functional Analysis · Mathematics 2019-10-30 Javier Duoandikoetxea , Marcel Rosenthal

In this paper, we establish several characterizations of the $A$-parallelism of bounded linear operators with respect to the seminorm induced by a positive operator $A$ acting on a complex Hilbert space. Among other things, we investigate…

Functional Analysis · Mathematics 2020-07-02 Tamara Bottazzi , Cristian Conde , Kais Feki

There is a resent paper claiming that every hyponormal operator which is not a multiple of the identity (operator) has a nontrivial hyperinvariant subspace. If this claim is true, then every hyponormal operator has a nontrivial invariant…

Functional Analysis · Mathematics 2024-01-30 Junfeng Liu

For a hyponormal operator, C. R. Putnam's inequality gives an upper bound on the norm of its self-commutator. In the special case of a Toeplitz operator with analytic symbol in the Smirnov space of a domain, there is also a geometric lower…

Functional Analysis · Mathematics 2014-11-13 Steven R. Bell , Timothy Ferguson , Erik Lundberg

We study the relationship between operators, orthonormal basis of subspaces and frames of subspaces (also called fusion frames) for a separable Hilbert space $\mathcal{H}$. We get sufficient conditions on an orthonormal basis of subspaces…

Functional Analysis · Mathematics 2011-11-10 Mariano A. Ruiz , Demetrio Stojanoff
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