6 papers
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…
Harnack parts for some truncated shifts
Gilles Cassier, Mohammed Benharrat
The purpose of this paper is to analysis the Harnack part of some truncated shifts whose -numerical radius equal one in the finite dimensional case. As pointed out in Theorem 1.…
Right and left quotient of two bounded operators on Hilbert spaces
Mohammed Benharrat
We define a left quotient as well as a right quotient of two bounded operators between Hilbert spaces, and we parametrize these two concepts using the Moore-Penrose inverse. In par…