Results 11 to 20 of about 446 (70)
On the classes of (n,m)-power D-normal and (n,m)-power D-quasi-normal operators
Operators and Matrices, 2019 This paper is devoted to the study of some new classes of operators on Hilbert space called (n,m) -power D -normal ( [(n,m)DN] ) and (n,m) -power D -quasi-normal ( [(n,m)DQN] ) , associated with a Drazin invertible operator using its Drazin inverse. Some
S. Mahmoud, O. Ahmed
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International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 31, Page 1993-2002, 2003., 2003 We introduce the concept of quasireducible operators. Basic properties and illustrative examples are considered in some detail in order to situate the class of quasireducible operators in its due place. In particular, it is shown that every quasinormal operator is quasireducible. The following result links this class with the invariant subspace problem:
C. S. Kubrusly
wiley +1 more source
On the largest analytic set for cyclic operators
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 30, Page 1899-1909, 2003., 2003 We describe the set of analytic bounded point evaluations for an arbitrary cyclic bounded linear operator T on a Hilbert space ℋ; some related consequences are discussed. Furthermore, we show that two densely similar cyclic Banach‐space operators possessing Bishop′s property (β) have equal approximate point spectra.
A. Bourhim
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Some versions of Anderson′s and Maher′s inequalities I
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 52, Page 3281-3297, 2003., 2003 We prove the orthogonality (in the sense of Birkhoff) of the range and the kernel of an important class of elementary operators with respect to the Schatten p‐class.
Salah Mecheri
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Hyponormality and subnormality for powers of commuting pairs of subnormal operators [PDF]
, 2006 Let H_0 (resp. H_\infty denote the class of commuting pairs of subnormal operators on Hilbert space (resp. subnormal pairs), and for an integer k>=1 let H_k denote the class of k-hyponormal pairs in H_0.
Curto, Raul E. +2 more
core +3 more sources
Generalized derivation modulo the ideal of all compact operators
International Journal of Mathematics and Mathematical Sciences, Volume 32, Issue 8, Page 501-506, 2002., 2002 We give some results concerning the orthogonality of the range and the kernel of a generalized derivation modulo the ideal of all compact operators.
Salah Mecheri, Ahmed Bachir
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Unbounded quasinormal operators revisited [PDF]
, 2013 Various characterizations of unbounded closed densely defined operators commuting with the spectral measures of their moduli are established.In particular, Kaufman's definition of an unbounded quasinormal operator is shown to coincide with that given by ...
Jablonski, Zenon Jan +2 more
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Hyponormal Toeplitz operators on the Bergman space
, 2017 A Hilbert space operator is hyponormal if T ∗T − TT ∗ is positive. We consider hyponormality of Toeplitz operators on the Bergman space with a symbol in the class of f + g where f is a monomial and g is a polynomial.
Houcine Sadraoui, M. Guediri
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Strongly exposed points in the unit ball of trace‐class operators
International Journal of Mathematics and Mathematical Sciences, Volume 30, Issue 7, Page 393-397, 2002., 2002 A theorem of Arazy shows that every extreme point of the unit ball of trace‐class operators is strongly exposed. We give this result a simpler and direct proof here.
Kourosh Nourouzi
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Berezin number inequalities for operators
Concrete Operators, 2019 The Berezin transform à of an operator A, acting on the reproducing kernel Hilbert space ℋ = ℋ (Ω) over some (non-empty) set Ω, is defined by Ã(λ) = 〉Aǩ λ, ǩ λ〈 (λ ∈ Ω), where k⌢λ=kλ‖kλ‖${\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\frown ...
Bakherad Mojtaba, Garayev Mubariz T.
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