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math.FA2024
Some Sharp bounds for the generalized Davis-Wielandt radius
Mehdi Naimi, Mohammed Benharrat, Faouzi Hireche
This paper presents a study of the generalized Davis-Wielandt radius of Hilbert space operators. New lower bounds for the generalized Davis-Wielandt radius and numerical radius are…
math.FA2021
On the circular numerical range of 5-by-5 partial isometries
Mehdi Naimi, Mohammed Benharrat
We prove, in some cases in term of kippenhahn curve, that if 5-by-5 partial isometry whose numerical range is a circular disc then its center is must be the origin. This gives a pa…