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We prove several lower bounds for the norm of a truncated Toeplitz operator and obtain a curious relationship between the $H^2$ and $H^{\infty}$ norms of functions in model spaces.

Functional Analysis · Mathematics 2009-07-20 Stephan Ramon Garcia , William T. Ross

This paper introduces a new family of semi-norms, say $\sigma_\mu$-Berezin norm on the space of all bounded linear operators $B(\mathcal{H})$ defined on a reproducing kernel Hilbert space $\mathcal{H}$, namely, for each $\mu \in [0,1]$ and…

Functional Analysis · Mathematics 2025-07-31 Athul Augustine , P. Hiran Das , Pintu Bhunia , P. Shankar

We prove the operator space Grothendieck inequality for bilinear forms on subspaces of noncommutative $L_p$-spaces with $2<p<\infty$. One of our results states that given a map $u: E\to F^*$, where $E, F\subset L_p(M)$ ($2<p<\infty$, $M$…

Functional Analysis · Mathematics 2007-05-23 Quanhua Xu

In this paper, we study the further improvements of the reverse Young and Heinz inequalities for the wider range of $v$, namely $v\in \mathbb{R}$. These modified inequalities are used to establish corresponding operator inequalities on a…

Classical Analysis and ODEs · Mathematics 2018-02-01 Shigeru Furuichi , Mohammad Bagher Ghaemi , Nahid Gharakhanlu

This study presents new upper bounds for the numerical radii of operator matrices, with a focus on $n \times n$ and $2 \times 2$ block matrices acting on Hilbert space direct sums. By employing techniques such as the H\"older-McCarthy…

Functional Analysis · Mathematics 2025-08-05 M. H. M. Rashid

In this work we establish sharp kernel conditions ensuring that the corresponding integral operators belong to Schatten-von Neumann classes. The conditions are given in terms of the spectral properties of operators acting on the kernel. As…

Functional Analysis · Mathematics 2021-05-31 Julio Delgado , Michael Ruzhansky

In this paper, we enlarge the space of uniformly supported pseudo-differential operators on some groupoids by considering kernels satisfying certain asymptotic estimates. We show that such enlarged space contains the compact parametrix, and…

Analysis of PDEs · Mathematics 2013-02-28 Bing Kwan So

In this note, we introduce a novel norm, termed the $t-$Berezin norm, on the algebra of all bounded linear operators defined on a reproducing kernel Hilbert space $\mathcal{H}$ as $$\|A\|_{t-ber} = \sup_{ \lambda, \mu \in \Omega} \left\{…

Functional Analysis · Mathematics 2025-04-10 Raj Kumar Nayak , Pintu Bhunia

We present a unified and concise method for establishing L^p Hardy and Rellich inequalities for a broad class of subelliptic operators of divergence type. The approach, based on a fundamental algebraic identity, provides explicit control on…

Analysis of PDEs · Mathematics 2026-04-27 Lorenzo D'Arca

In this paper, for $1\leq p<\infty$, we provide several descriptions of Schatten $p$-class Hankel operators $H_f$ and $H_{\overline{f}}$ on the weight Bergman space $A^2_\omega$, in terms of a certain global and local mean oscillation of…

Functional Analysis · Mathematics 2023-12-01 Hamzeh Keshavarzi , Fanglei Wu

Changes of some unitarily invariant norms and anti-norms under the operation of partial trace are examined. The norms considered form a two-parametric family, including both the Ky Fan and Schatten norms as particular cases. The obtained…

Quantum Physics · Physics 2012-11-02 Alexey E. Rastegin

Following previous works for the unit ball, we define quasi-radial pseudo-homogeneous symbols on the projective space and obtain the corresponding commutativity results for Toeplitz operators. A geometric interpretation of these symbols in…

Functional Analysis · Mathematics 2016-08-31 Miguel Antonio Morales-Ramos , Raúl Quiroga-Barranco , Armando Sánchez-Nungaray

We describe the Aluthge transform of an unbounded weighted composition operator acting in an $L^2$-space. We show that its closure is also a weighted composition operator with the same symbol and a modified weight function. We investigate…

Functional Analysis · Mathematics 2024-11-27 Chafiq Benhida , Piotr Budzynski , Jacek Trepkowski

Given a compact manifold $M$ with boundary $\partial M$, in this paper we introduce a global symbolic calculus of pseudo-differential operators associated to $(M,\partial M)$. The symbols of operators with boundary conditions on $\partial…

Analysis of PDEs · Mathematics 2015-12-23 Julio Delgado , Michael Ruzhansky , Niyaz Tokmagambetov

In this paper we first study the generalized weighted Hardy spaces $H^p_{L,w}(X)$ for $0<p\le 1$ associated to nonnegative self-adjoint operators $L$ satisfying Gaussian upper bounds on the space of homogeneous type $X$ in both cases of…

Analysis of PDEs · Mathematics 2018-08-30 The Anh Bui , Xuan Thinh Duong

We are interested in the harmonic analysis on $p$-adic homogeneous spaces based on spherical functions. In the present paper, we investigate the space $X$ of unitary hermitian matrices of odd size over a ${\mathfrak p}$-adic field of odd…

Number Theory · Mathematics 2015-02-19 Yumiko Hironaka , Yasushi Komori

In this article, we prove an inner product inequality for Hilbert space operators. This inequality, then, is utilized to present a general numerical radius inequality using convex functions. Applications of the new results include obtaining…

Functional Analysis · Mathematics 2022-07-19 Zahra Heydarbeygi , Mohammad Sababheh , Hamid Reza Moradi

In this survey, we shall present characterizations of some distinguished classes of Hilbertian bounded linear operators (namely, normal operators, selfadjoint operators, and unitary operators) in terms of operator inequalities related to…

Functional Analysis · Mathematics 2020-07-03 Ameur Seddik

This paper offers a unified approach to determining when two generalized Toeplitz operators on L^2 are equivalent. This will be done through multipliers between closed subspaces of L^2. Our discussion will include Toeplitz operators (and…

Functional Analysis · Mathematics 2023-07-12 Cristina Camara , Carlos Carteiro. William T. Ross

It is well known that the essential norm of a Toeplitz operator on the Hardy space $H^p(\mathbb{T})$, $1 < p < \infty$ is greater than or equal to the $L^\infty(\mathbb{T})$ norm of its symbol. In 1988, A. B\"ottcher, N. Krupnik, and B.…

Functional Analysis · Mathematics 2020-07-28 Eugene Shargorodsky