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Based on a judicious partitioning of the preimage of the pseudohyperbolic disk under the composition symbols, in this article, we show that the boundedness and compactness of the sum of two generalized weighted composition operators with…

Complex Variables · Mathematics 2025-09-03 Juntao Du , Zuoling Liu

For any positive invertible matrix $A$ and any normal matrix $B$ in $M_{n}({\Bbb C})$, we investigate whether the inequality $ ||A\sharp (B^{*}A^{-1}B)||\geq ||B|| $ is true or not, where $\sharp$ denotes the geometric mean and $||\cdot||$…

Functional Analysis · Mathematics 2017-10-18 Tomohiro Hayashi

We complement a recent result of S. Furuichi, by showing that the differences $\sum_{i=1}^n \alpha_i x_i - \prod_{i=1}^n x_i^{\alpha_i}$ associated to distinct sequences of weights are comparable, with constants that depend on the smallest…

Classical Analysis and ODEs · Mathematics 2010-10-08 J. M. Aldaz

In this article we prove weighted norm inequalities and pointwise estimates between the multilinear fractional integral operator and the multilinear fractional maximal. As a consequence of these estimations we obtain weighted weak and…

Analysis of PDEs · Mathematics 2009-07-31 Gladis Pradolini

We completely characterize Birkhoff-James orthogonality with respect to numerical radius norm in the space of bounded linear operators on a complex Hilbert space. As applications of the results obtained, we estimate lower bounds of…

Functional Analysis · Mathematics 2024-08-13 Arpita Mal , Kallol Paul , Jeet Sen

Inspired by the recent work by R.Pal et al., we give further refined inequalities for a convex Riemann integrable function, applying the standard Hermite-Hadamard inequality. Our approach is different from their one in \cite{PSMA2016}. As…

Classical Analysis and ODEs · Mathematics 2020-04-08 Shigeru Furuichi , Nicuşor Minculete

We present sharp lower bounds for the A-numerical radius of semi-Hilbertian space operators. We also present an upper bound. Further we compute new upper bounds for the $B$-numerical radius of $2 \times 2$ operator matrices where $B =…

Functional Analysis · Mathematics 2020-04-22 Pintu Bhunia , Raj Kumar Nayak , Kallol Paul

In this short note, we study the properties of the weighted Frechet mean as a convex combination operator on an arbitrary metric space, (Y,d). We show that this binary operator is commutative, non-associative, idempotent, invariant to…

Statistics Theory · Mathematics 2012-06-13 Cedric E. Ginestet , Andrew Simmons , Eric D. Kolaczyk

We study bounds for the backward shift operator $f \mapsto (f(z)-f(0))/z$ and the related operator $f \mapsto f - f(0)$ on Hardy and Bergman spaces of analytic and harmonic functions. If $u$ is a real valued harmonic function, we also find…

Complex Variables · Mathematics 2017-02-14 Timothy Ferguson

Eve (2003), studied seven means from geometrical point of view. These means are \textit{Harmonic, Geometric, Arithmetic, Heronian, Contra-harmonic, Root-mean square and Centroidal mean}. Some of these means are particular cases of Gini's…

History and Overview · Mathematics 2012-03-13 Inder Jeet Taneja

We study Hardy type inequalities involving mixed cylindrical and spherical weights, for functions supported in cones. These inequalities are related to some singular or degenerate differential operators.

Analysis of PDEs · Mathematics 2023-05-10 Gabriele Cora , Roberta Musina , Alexander I. Nazarov

It is shown that Newton's inequalities and the related Maclaurin's inequalities provide several refinements of the fundamental Arithmetic mean - Geometric mean - Harmonic mean inequality in terms of the means and variance of positive real…

Statistics Theory · Mathematics 2017-02-16 R. Sharma , A. Sharma , R. Saini , G. Kapoor

We study the harmonic mean of non-zero complex-valued random variables (complex harmonic mean) and establish several geometric estimates and bounds. In contrast to the classical positive-valued case, complex harmonic means may lie outside…

Complex Variables · Mathematics 2026-02-10 Atsushi Nakayasu

In this article, we explore the celebrated Gr\"{u}ss inequality, where we present a new approach using the Gr\"{u}ss inequality to obtain new refinements of operator means inequalities. We also present several operator Gr\"{u}ss-type…

Functional Analysis · Mathematics 2020-09-17 H. R. Moradi , S. Furuichi , Z. Heydarbeygi , M. Sababheh

When an eigenvector of a semi-bounded operator is positive, we show that a remarkably simple argument allows to obtain upper and lower bounds for its associated eigenvalue. This theorem is a substantial generalization of Barta-like…

Spectral Theory · Mathematics 2009-11-11 Amaury Mouchet

Mercer inequality for convex functions is a variant of Jensen's inequality, with an operator version that is still valid without operator convexity. This paper is two folded. First, we present a Mercer-type inequality for operators without…

Functional Analysis · Mathematics 2020-03-06 H. R. Moradi , S. Furuichi , M. Sababheh

We show that an almost trivial inequality for the first and second mean of a random variable can be used to give non-trivial improvements on deep results. As applications we improve on results on lower bounds for the Riemann zeta-function…

Probability · Mathematics 2011-05-10 Jan-Christoph Schlage-Puchta

In this paper, we improve the famous Reid Inequality related to linear operators. Some monotony results for positive operators are also established with a different approach from what is known in the existing literature. Lastly, Reid and…

Functional Analysis · Mathematics 2017-07-12 Souheyb Dehimi , Mohammed Hichem Mortad

We reformulate the notion of uncertainty of pairs of unitary operators within the context of guessing games and derive an entropic uncertainty relation for a pair of such operators. We show how distinguishable operators are compatible while…

Quantum Physics · Physics 2023-06-05 Jesni Shamsul Shaari , Rinie N. M. Nasir , Stefano Mancini

Weighted and controlled frames have been introduced recently to improve the numerical efficiency of iterative algorithms for inverting the frame operator. In this paper we develop systematically these notions, including their mutual…

Functional Analysis · Mathematics 2010-07-08 Peter Balazs , Jean-Pierre Antoine , Anna Grybos