New upper bounds for the numerical radius of Hilbert space operators

2021 ◽  
Vol 167 ◽  
pp. 102959
Author(s):  
Pintu Bhunia ◽  
Kallol Paul
Keyword(s):  
Hilbert Space ◽  
Upper Bounds ◽  
Numerical Radius ◽  
Hilbert Space Operators

Numerical radius inequalities for products of Hilbert space operators

2014 ◽  
Vol 72 (2) ◽  
pp. 521-527 ◽  
Author(s):  
Amer Abu-Omar ◽  
Fuad Kittaneh
Keyword(s):  
Hilbert Space ◽  
Numerical Radius ◽  
Hilbert Space Operators

Some reverse and numerical radius inequalities

2018 ◽  
Vol 68 (5) ◽  
pp. 1121-1128
Author(s):  
Mohsen Shah Hosseini ◽  
Mohsen Erfanian Omidvar
Keyword(s):  
Hilbert Space ◽  
Numerical Radius ◽  
Hilbert Space Operators

Abstract In this paper, we present several numerical radius inequalities for Hilbert space operators. More precisely, we prove if $ T,U\in\mathbb{B}\left(\mathcal{H}\right) $ such that U is unitary, then $$\displaystyle\omega(TU\pm U^{*}T)\leq 2\sqrt{\omega(T^{2})+\|T\pm T^{*}\|^{2}}. $$ Also, we have compared our results with some known outcomes.

SOME INEQUALITIES FOR THE NUMERICAL RADIUS FOR HILBERT SPACE OPERATORS

2016 ◽  
Vol 94 (3) ◽  
pp. 489-496 ◽  
Author(s):  
MOHSEN SHAH HOSSEINI ◽  
MOHSEN ERFANIAN OMIDVAR
Keyword(s):  
Hilbert Space ◽  
Invertible Operator ◽  
Numerical Radius ◽  
Hilbert Space Operators

We introduce some new refinements of numerical radius inequalities for Hilbert space invertible operators. More precisely, we prove that if $T\in {\mathcal{B}}({\mathcal{H}})$ is an invertible operator, then $\Vert T\Vert \leq \sqrt{2}\unicode[STIX]{x1D714}(T)$.

Numerical Radius Inequalities for Commutators of Hilbert Space Operators

2011 ◽  
Vol 32 (7) ◽  
pp. 739-749 ◽  
Author(s):  
Omar Hirzallah ◽  
Fuad Kittaneh ◽  
Khalid Shebrawi
Keyword(s):  
Hilbert Space ◽  
Numerical Radius ◽  
Hilbert Space Operators
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