Results 11 to 20 of about 51 (51)

Numerical Range on Weighted Hardy Spaces as Semi Inner Product Spaces

Analele Stiintifice ale Universitatii Ovidius Constanta: Seria Matematica, 2017
The semi-inner product, in the sense of Lumer, on weighted Hardy space which generate the norm is unique. Also we will discuss some properties of the numerical range of bounded linear operators on weighted Hardy spaces.
Heydari Mohammad Taghi
doaj   +1 more source

A class of tridiagonal operators associated to some subshifts

Open Mathematics, 2016
We consider a class of tridiagonal operators induced by not necessary pseudoergodic biinfinite sequences. Using only elementary techniques we prove that the numerical range of such operators is contained in the convex hull of the union of the numerical ...
Hernández-Becerra Christian, Itzá-Ortiz Benjamín A.   +1 more
doaj   +1 more source

Determinantal inequalities for J -accretive dissipative matrices

, 2017
In this note we determine bounds for the determinant of the sum of two J -accretive dissipative matrices with prescribed spectra.
BEBIANO, Natália, DA PROVIDÊNCIA , João   +1 more
core   +1 more source

Hilbert–Schmidt‐Type Radii of Operator Pairs

Journal of Function Spaces, Volume 2025, Issue 1, 2025.
Let C2H be the Hilbert–Schmidt class on a complex separable Hilbert space H. In light of the recent definition of the weighted numerical radius and motivated by the definition of the Hilbert–Schmidt numerical radius of a pair of operators, we introduce the definition of the weighted Hilbert–Schmidt numerical radius of a pair of operators.
Bashar Mayyas, Mohammad Sababheh, Raúl E. Curto   +2 more
wiley   +1 more source

Generalized Derivations and Norm Equality in Normed Ideals [PDF]

, 2011
2000 Mathematics Subject Classification: 47A10, 47A12, 47A30, 47B10, 47B20, 47B37, 47B47, 47D50.We compare the norm of a generalized derivation on a Hilbert space with the norm of its restrictions to Schatten norm ...
Barraa, Mohamed
core  

Convexity around the Unit of a Banach Algebra [PDF]

, 2008
2000 Mathematics Subject Classification: Primary: 46B20. Secondary: 46H99, 47A12.We estimate the (midpoint) modulus of convexity at the unit 1 of a Banach algebra A showing that inf {max±||1 ± x|| − 1 : x ∈ A, ||x||=ε} ≥ (π/4e)ε²+o(ε²) as ε → 0. We also
Vishnyakova, Anna, Martín, Miguel, Kadets, Vladimir, Katkova, Olga   +3 more
core  

Function theory, geometry, and circular numerical ranges

Concrete Operators
We introduce the reader to partial isometries and their properties. In particular, we consider the Gau-Wang-Wu conjecture from 2016: When is the numerical range of a partial isometry circular?
Adams Gregory, Gorkin Pamela
doaj   +1 more source

Domaine Numérique du produit AB avec A normal [PDF]

, 2006
2000 Mathematics Subject Classification: 18B30, 47A12.Let A, B be two linear operators on a complex Hilbert space H. We extend a Bouldin's result (1969) conserning W(AB) - the numerical range of the product AB. We show, when AB = BA and A is normal, than
Kaadoud, Mohamed Chraïbi
core  

EP Elements in Rings and in Semigroups with Involution and in C*-algebras [PDF]

, 2015
This work includes a survey of most of the results concerning EP elements in semigroups and rings with involution and in C*-algebras. 2010 Mathematics Subject Classification: Primary 46L05, 46J05, 46H05, 46H30, 47A05, 47A53, 47A60, 15A09, 15A33, 16A28 ...
Karanasios, Sotirios
core  

On Berezin norm and Berezin number inequalities for sum of operators

Demonstratio Mathematica
The aim of this study is to obtain several inequalities involving the Berezin number and the Berezin norm for various combinations of operators acting on a reproducing kernel Hilbert space.
Altwaijry Najla, Feki Kais, Minculete Nicusor   +2 more
doaj   +1 more source