[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 …
counterexamples are patently examples but with a different purpose. The commonly agreed …
[图书][B] An operator theory problem book
MH Mortad - 2018 - books.google.com
This book is for third and fourth year university mathematics students (and Master students)
as well as lecturers and tutors in mathematics and anyone who needs the basic facts on …
as well as lecturers and tutors in mathematics and anyone who needs the basic facts on …
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 …
a one-variable complex polynomial, and T is an unbounded, densely defined, and linear …
On the absolute value of unbounded operators
The primary purpose of the present paper is to investigate when relations of the types| AB|=|
A|| B|,| A±B|≤| A|+| B|,|| A|—| B||≤| A±B| and| Re A|≤| A|(among others) hold in an …
A|| B|,| A±B|≤| A|+| B|,|| A|—| B||≤| A±B| and| Re A|≤| A|(among others) hold in an …
On normal products of selfadjoint operators
A necessary and sufficient condition for the product AB of a selfadjoint operator A and a
bounded selfadjoint operator B to be normal is given. Various properties of the factors of the …
bounded selfadjoint operator B to be normal is given. Various properties of the factors of the …
Maximality of linear operators
M Meziane, MH Mortad - Rendiconti del Circolo Matematico di Palermo …, 2019 - Springer
Maximality of linear operators | SpringerLink Skip to main content Advertisement SpringerLink
Account Menu Find a journal Publish with us Search Cart 1.Home 2.Rendiconti del Circolo …
Account Menu Find a journal Publish with us Search Cart 1.Home 2.Rendiconti del Circolo …
The Fuglede theorem and some intertwining relations
IFZ Bensaid, S Dehimi, B Fuglede… - Advances in Operator …, 2021 - Springer
In this paper, we show new versions of the Fuglede theorem in an unbounded setting. A
related counterexample is also presented. In the second part of the paper, we give a pair of …
related counterexample is also presented. In the second part of the paper, we give a pair of …
On the absolute value of the product and the sum of linear operators
MH Mortad - Rendiconti del Circolo Matematico di Palermo Series 2, 2019 - Springer
Abstract Let A, B ∈ B (H) A, B∈ B (H). In the present paper, we establish simple and
interesting facts on when we have| A|| B|=| B|| A|| A|| B|=| B|| A|,| AB|=| A|| B|| AB|=| A|| B|,| A ± …
interesting facts on when we have| A|| B|=| B|| A|| A|| B|=| B|| A|,| AB|=| A|| B|| AB|=| A|| B|,| A ± …
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 …
three generalizations of this version, each of which involves unbounded normal operators …