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We provide a number of sharp inequalities involving the usual operator norms of Hilbert space operators and powers of the numerical radii. Based on the traditional convexity inequalities for nonnegative real numbers and some generalize…

Functional Analysis · Mathematics 2023-07-24 M. H. M Rashid , Feras Bani-Ahmad

50 years after Thompson's famous triangle inequality for the operator right modulus, we establish a triangle inequality for the quadratic symmetric modulus. We also discuss the corresponding equality cases as well as the…

Functional Analysis · Mathematics 2026-04-17 Teng Zhang

We develop several upper and lower bounds for the $A$-Euclidean operator radius of $2$-tuple operators admitting $A$-adjoint, and show that they refine the earlier related bounds. As an application of the bounds developed here, we obtain…

Functional Analysis · Mathematics 2024-08-14 Suvendu Jana , Pintu Bhunia , Kallol Paul

Several numerical radius inequalities are studied by developing an extension of the Buzano's inequality. It is shown that if $T$ is a bounded linear operator on a complex Hilbert space, then \begin{eqnarray*} w^n(T) &\leq& \frac{1}{2^{n-1}}…

Functional Analysis · Mathematics 2023-05-30 Pintu Bhunia

Let $A$ be a bounded linear operator defined on a complex Hilbert space and let $|A|=(A^*A)^{1/2}$ be the positive square root of $A$. Among other refinements of the well known numerical radius inequality $w^2(A)\leq \frac12 \|A^*A+AA^*\|$,…

Functional Analysis · Mathematics 2024-08-14 Suvendu Jana , Pintu Bhunia , Kallol Paul

This paper presents a study of the generalized Davis-Wielandt radius of Hilbert space operators. New lower bounds for the generalized Davis-Wielandt radius and numerical radius are provided. An alternative of the triangular inequality for…

Functional Analysis · Mathematics 2026-03-05 Mehdi Naimi , Mohammed Benharrat , Faouzi Hireche

We present a complete system of inequalities for the inradius, circumradius, and diameter in the $3$-dimensional Euclidean space. To do so, we prove quasiconcavity of the inradius evaluated over $n$-simplices with a common facet…

Metric Geometry · Mathematics 2025-09-08 René Brandenberg , Bernardo González Merino , Mia Runge

New inequalities for the $A$-numerical radius of the products and sums of operators acting on a semi-Hilbert space, i.e. a space generated by a positive semidefinite operator $A$, are established. In particular, it is proved for operators…

Functional Analysis · Mathematics 2020-12-23 Pintu Bhunia , Kais Feki , Kallol Paul

Some inequalities for the ratios of generalized digamma functions are presented. The approache makes use of the series representations of the $(q,k)$-digamma and $(p,q)$-digamma functions.

Classical Analysis and ODEs · Mathematics 2014-08-18 Kwara Nantomah

We describe all isometries of the $q$-numerical radius on the space ${\mathcal K}(\mathcal H)$ of compact operators on a (possibly infinite-dimensional) Hilbert space $\mathcal H$.

Functional Analysis · Mathematics 2021-02-18 Maria Inez Cardoso Gonçalves , Vladimir G. Pestov

In this article we prove new inequalities for the generalized and the joint spectral radius of bounded sets of positive operators on Banach function and sequence spaces, in particular some inequalities for positive kernel operators that…

Functional Analysis · Mathematics 2023-11-07 Katarina Bogdanović

We completely characterize the Crawford number attainment set and the numerical radius attainment set of a bounded linear operator on a Hilbert space. We study the intersection properties of the corresponding attainment sets of numerical…

Functional Analysis · Mathematics 2020-01-28 Debmalya Sain , Arpita Mal , Pintu Bhunia , Kallol Paul

In this paper, the authors establish some inequalities involving the $q$-extension of the classical Gamma function. These inequalities provide bounds for certain ratios of the $q$-extended Gamma function. The procedure makes use of…

Classical Analysis and ODEs · Mathematics 2015-10-14 Kwara Nantomah , Edward Prempeh , Stephen Boakye Twum

In this paper, we introduce the concept of operator arithmetic-geometrically convex functions for positive linear operators and prove some Hermite-Hadamard type inequalities for these functions. As applications, we obtain trace inequalities…

Functional Analysis · Mathematics 2016-03-16 Ali Taghavi , Vahid Darvish , Haji Mohammad Nazari

In this article, firstly, some simple and smoothness properties of the weighted numerical radius and the weighted Crawford number functions are investigated. Then, some generalization formulas for lower and upper bounds of the weighted…

Functional Analysis · Mathematics 2024-12-31 Zameddin I. Ismailov , Pembe Ipek Al

In this paper, we present various inequalities for generalized numerical radius of $2 \times 2$ block matrices for Schatten p-norm. Moreover, we give a refinement of the triangle inequality for the Schatten p-generalized numerical radius.

Functional Analysis · Mathematics 2022-04-07 Jana Hamza , Hassan Issa

We present here necessary and sufficient conditions for the invertibility of circulant and symmetric matrices that depend on three parameters and moreover, we explicitly compute the inverse. The techniques we use are related with the…

Classical Analysis and ODEs · Mathematics 2015-05-30 A. Carmona , A. M. Encinas , S. Gago , M. J. Jiménez , M. Mitjana

We present several sharp upper bounds and some extension for product operators. Among other inequalities, it is shown that if , , are non-negative continuous functions on such that , , then for all non-negative operator monotone decreasing…

Functional Analysis · Mathematics 2020-04-22 Hosna Jafarmanesh , Maryam Khosravi

Using the polar decomposition of a bounded linear operator $A$ defined on a complex Hilbert space, we obtain several numerical radius inequalities of the operator $A$, which generalize and improve the earlier related ones. Among other…

Functional Analysis · Mathematics 2023-03-07 Pintu Bhunia

This paper is devoted to a systematic study of certain geometric integral inequalities which arise in continuum combinatorial approaches to $L^p$-improving inequalities for Radon-like transforms over polynomial submanifolds of intermediate…

Classical Analysis and ODEs · Mathematics 2022-03-23 Philip T Gressman
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