Research Article

Numerical radius inequalities for the off-diagonal parts of 2 × 2 operator matrices

Published in: Quaestiones Mathematicae
Volume 46 , issue 11 , 2023 , pages: 2277–2286

DOI: 10.2989/16073606.2022.2150584

Author(s): Aicha Ammar Mustapha Stambouli University, Algeria , Abdelkader Frakis Mustapha Stambouli University, Algeria , Fuad Kittaneh The University of Jordan, Jordan

Keywords: Primary: 47A12 , Secondary: 47A30 , Operator matrix , numerical radius , operator norm , inequality

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Abstract

We give some new bounds for the numerical radii of the off-diagonal parts of 2 × 2 operator matrices. A refinement of the triangle inequality for the operator norm is also given.

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