Results 11 to 20 of about 64 (56)
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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Proper contractions and invariant subspaces
International Journal of Mathematics and Mathematical Sciences, Volume 28, Issue 4, Page 223-230, 2001., 2001 Let T be a contraction and A the strong limit of {T∗nTn}n ≥ 1. We prove the following theorem: if a hyponormal contraction T does not have a nontrivial invariant subspace, then T is either a proper contraction of class 𝒞00 or a nonstrict proper contraction of class 𝒞10 for which A is a completely nonprojective nonstrict proper contraction.
C. S. Kubrusly, N. Levan
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On Quasi-invertibility and Quasi-similarity of Operators in Hilbert Space. [PDF]
, 2018 In this paper we show that if two operators A and B are quasi-invertible then AB and BA are also quasi-similar. We also show that if two operators and are isometric is consistent in invertibility under further hypothesis.
S.W., Luketero +2 more
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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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Some remarks on the invariant subspace problem for hyponormal operators
International Journal of Mathematics and Mathematical Sciences, Volume 28, Issue 6, Page 359-365, 2001., 2001 We make some remarks concerning the invariant subspace problem for hyponormal operators. In particular, we bring together various hypotheses that must hold for a hyponormal operator without nontrivial invariant subspaces, and we discuss the existence of such operators.
Vasile Lauric
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Product and factorization of hypo-EP operators
Special Matrices, 2018 In this article, we derive some necessary and sufficient conditions for the product of hypo-EP operators to be hypo-EP and we characterize hypo-EP operators through factorizations.
Johnson P. Sam, Vinoth A.
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On the projection constants of some topological spaces and some applications
Abstract and Applied Analysis, Volume 6, Issue 5, Page 299-308, 2001., 2001 We find a lower estimation for the projection constant of the projective tensor product X⊗ ∧Y and the injective tensor product X⊗ ∨Y, we apply this estimation on some previous results, and we also introduce a new concept of the projection constants of operators rather than that defined for Banach spaces.
Entisarat El-Shobaky +2 more
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On the class of (A,n) - real power positive operators in semi-hilbertian space [PDF]
, 2019 In this paper, the concept of the class of n-Real power positive operators on a hilbert space defined by Abdelkader Benali in [1] is generalized when an additional semi-inner product is considered.
Benali, Abdelkader
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Some results on dominant operators
International Journal of Mathematics and Mathematical Sciences, Volume 21, Issue 2, Page 217-220, 1998., 1997 We show that the Weyl spectrum of a dominant operator satisfies the spectral mapping theorem for analytic functions and then answer a question of Oberai.
Youngoh Yang
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SOME RESULTS ON OPERATORS CONSISTENT IN INVERTIBILITY [PDF]
, 2018 In this paper, we investigate the conditions under which some classes of operators in a complex Hilbert space H are said to be consistent in invertibility.
Wabuya, Kikete, Stephen, Luketero
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