[图书][B] Counterexamples in operator theory

MH Mortad - 2022 - Springer
Counterexamples undeniably play an outstanding role in mathematics. As is known,
counterexamples are patently examples but with a different purpose. The commonly agreed …

Certain properties involving the unbounded operators p (T), TT⁎, and T⁎ T; and some applications to powers and nth roots of unbounded operators

MH Mortad - Journal of Mathematical Analysis and Applications, 2023 - Elsevier
In this paper, we are concerned with conditions under which [p (T)]⁎= p‾(T⁎), where p (z) is
a one-variable complex polynomial, and T is an unbounded, densely defined, and linear …

Conditions Implying Self-adjointness and Normality of Operators

H Stanković - Complex Analysis and Operator Theory, 2024 - Springer
In this paper, we give new characterizations of self-adjoint and normal operators on a Hilbert
space H. Among other results, we show that if H is a finite-dimensional Hilbert space and …

[PDF][PDF] Unbounded generalizations of the Fuglede-Putnam theorem

S Dehimi, MH Mortad, A Bachir - arXiv preprint arXiv:2203.06715, 2022 - arxiv.org
arXiv:2203.06715v1 [math.FA] 13 Mar 2022 Page 1 arXiv:2203.06715v1 [math.FA] 13 Mar
2022 UNBOUNDED GENERALIZATIONS OF THE FUGLEDE-PUTNAM THEOREM SOUHEYB …

Generalizations of Weiss' version of the Fuglede–Putnam theorem for unbounded operators

MH Mortad - Expositiones Mathematicae, 2024 - Elsevier
The present paper discusses Weiss' version of the Fuglede–Putnam theorem. We establish
three generalizations of this version, each of which involves unbounded normal operators …

When nilpotence implies the zeroness of linear operators

N Frid, MH Mortad, S Dehimi - arXiv preprint arXiv:2008.09509, 2020 - arxiv.org
arXiv:2008.09509v2 [math.FA] 29 Apr 2022 Page 1 arXiv:2008.09509v2 [math.FA] 29 Apr 2022
WHEN NILPOTENCE IMPLIES THE ZERONESS OF LINEAR OPERATORS NASSIMA FRID …

On the reduction of powers of self-adjoint operators

S Kebli, MH Mortad - arXiv preprint arXiv:2407.13861, 2024 - arxiv.org
Let $ T\in B (H) $ be such that $ T^ n $ is self-adjoint for some $ n\in\mathbb {N} $ with $
n\geq 3$. The paper's primary aim is to establish the conditions that lead to the self …

Hyponormal measurable operators, affiliated to a semifinite von Neumann algebra

A Bikchentaev - Advances in Operator Theory, 2024 - Springer
Let M be a von Neumann algebra of operators on a Hilbert space H and τ be a faithful
normal semifinite trace on M, S (M, τ) be the∗-algebra of all τ-measurable operators …

[PDF][PDF] 两个无界线性算子乘积的共辄算子

徐宇飞, 吴德玉, 凌先冲, 葛畅, 吴霜… - Advances in Applied …, 2024 - pdf.hanspub.org
TABLE OF CONTENTS Page 1 Advances in Applied Mathematics, Vol.13, No.1, 1-484 应用
数学进展, 13 卷1 期 Published Online January 2024 in Hans (https://www.hanspub.org/journal/aam) …

[PDF][PDF] On the commutativity of unbounded unclosed symmetric operators

MS MOKTHAR-KHARROUBI… - Preprint posted on … - researchgate.net
ON THE COMMUTATIVITY OF UNBOUNDED UNCLOSED SYMMETRIC OPERATORS 1.
Introduction First, we assume readers are well acquainted with Page 1 ON THE …