Complementary bounds for the numerical and spectral radii

Published in: Quaestiones Mathematicae
Volume 48 , issue 6 , 2025 , pages: 863–877

DOI: 10.2989/16073606.2025.2458781

Author(s): Fuad Kittaneh The University of Jordan, Jordan , Hamid Reza Moradi Islamic Azad University, Iran , Mohammad Sababheh Princess Sumaya University for Technology, Jordan

Keywords: 47A12 , 47A30 , 47A63 , 47B47 , Numerical radius , spectral radius , operator matrix

Let denote the C* –algebra of all bounded linear operators on a Hilbert space . Among other results, we show that if are nonzero, then

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