7 papers · 1 filter
Harnack parts for 5-by-5 truncated shift with numerical radius one
Mohammed Benharrat
We provide a complete description of the Harnack part for normalized truncated shift of size five with numerical radius one. We prove that any operator in this Harnack component mu…
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…
The Moore-Penrose inverse of accretive operators with application to quadratic operator pencils
Fairouz Bouchelaghem, Mohammed Benharrat
We establish some relationships between an m-accretive operator and its Moore-Penorse inverse. We derive some perturbation result of the Moore-Penorse inverse of a maximal accretiv…
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…
A factorization of a quadratic pencils of accretive operators and applications
F. Bouchelaghem, M. Benharrat
A canonical factorization is given for a quadratic pencil of accretive operators in a Hilbert space. Also, we establish some relationships between an m-accretive operator and its M…
A perturbation result of m-accretive linear operators in Hilbert spaces
Mohammed Benharrat
A new sufficient condition is given for the sum of linear m-accretive operator and accretive operator one in a Hilbert space to be m-accretive. As an application, an extended resul…