[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 …
Right (or left) invertibility of bounded and unbounded operators and applications to the spectrum of products
Right (Or Left) Invertibility of Bounded and Unbounded Operators and Applications to the
Spectrum of Products Page 1 Complex Anal. Oper. Theory (2018) 12:589–597 https://doi.org/10.1007/s11785-017-0687-z …
Spectrum of Products Page 1 Complex Anal. Oper. Theory (2018) 12:589–597 https://doi.org/10.1007/s11785-017-0687-z …
[图书][B] The Fuglede-Putnam Theory
MH Mortad - 2022 - Springer
When I took a course on spectral theory some 25 years ago, the Fuglede theorem was not
part of the syllabus of that course. Indeed, that course was mainly directed toward …
part of the syllabus of that course. Indeed, that course was mainly directed toward …
Conditions implying commutativity of unbounded self-adjoint operators and related topics
K Gustafson, MH Mortad - Journal of Operator Theory, 2016 - JSTOR
Let B be a bounded self-adjoint operator and let A be a nonnegative self-adjoint unbounded
operator. It is shown that if BA is normal, it must be self-adjoint and so must be AB …
operator. It is shown that if BA is normal, it must be self-adjoint and so must be AB …
On the normality of the sum of two normal operators
MH Mortad - Complex Analysis and Operator Theory, 2012 - Springer
On the Normality of the Sum of Two Normal Operators Page 1 Complex Anal. Oper. Theory (2012)
6:105–112 DOI 10.1007/s11785-010-0072-7 Complex Analysis and Operator Theory On the …
6:105–112 DOI 10.1007/s11785-010-0072-7 Complex Analysis and Operator Theory On the …
On some product of two unbounded self-adjoint operators
MH Mortad - Integral Equations and Operator Theory, 2009 - Springer
We give a spectral analysis of some unbounded normal product HK of two self-adjoint
operators H and K (which appeared in [7]) and we say why it is not self-adjoint even if the …
operators H and K (which appeared in [7]) and we say why it is not self-adjoint even if the …