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Year 2024, Volume: 28, 375 - 381, 01.08.2024
https://doi.org/10.55549/epstem.1523566

Abstract

References

  • Al-Dolat, M. (2024). General upper bounds for the numerical radii of Hilbert space operators The Eurasia Proceedings of Science, Technology, Engineering & Mathematics (EPSTEM), 28, 375-381.

General Upper Bounds for the Numerical Radii of Hilbert Space Operators

Year 2024, Volume: 28, 375 - 381, 01.08.2024
https://doi.org/10.55549/epstem.1523566

Abstract

We present a collection upper bounds for the numerical radii of a certain 2 Γ— 2 operator matrices. We use these bounds to improve on some known numerical radius inequalities for powers of Hilbert space operators. In particular, we show that if 𝐴 is a bounded linear operator on a complex Hilbert space, then 𝑀 2π‘Ÿ (𝐴) ≀ 1+𝛼 8 β€–|𝐴| 2π‘Ÿ +|𝐴 βˆ— | 2π‘Ÿβ€–+ 1+𝛼 4 𝑀(|𝐴| π‘Ÿ |𝐴 βˆ— | π‘Ÿ )+ 1βˆ’π›Ό 2 𝑀 π‘Ÿ (𝐴 2 ) for every r β‰₯ 1 and Ξ± ∈ [0,1]. This substantially improves on the existing inequality 𝑀 2π‘Ÿ (𝐴) ≀ 1 2 β€–|𝐴| 2π‘Ÿ + |𝐴 βˆ— | 2π‘Ÿβ€–. Here 𝑀(. ) and ||. || denote the numerical radius and the usual operator norm, respectively.

References

  • Al-Dolat, M. (2024). General upper bounds for the numerical radii of Hilbert space operators The Eurasia Proceedings of Science, Technology, Engineering & Mathematics (EPSTEM), 28, 375-381.
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Details

Primary Language English
Subjects Software Engineering (Other)
Journal Section Articles
Authors

Mohammed Al- Dolat

Early Pub Date July 29, 2024
Publication Date August 1, 2024
Submission Date February 7, 2024
Acceptance Date April 22, 2024
Published in Issue Year 2024Volume: 28

Cite

APA Al- Dolat, M. (2024). General Upper Bounds for the Numerical Radii of Hilbert Space Operators. The Eurasia Proceedings of Science Technology Engineering and Mathematics, 28, 375-381. https://doi.org/10.55549/epstem.1523566