Essential spectra of quasisimilar -quasihyponormal operators.
Kim, An-Hyun, Kim, In Hyoun (2006)
Journal of Inequalities and Applications [electronic only]
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Kim, An-Hyun, Kim, In Hyoun (2006)
Journal of Inequalities and Applications [electronic only]
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L. A. Coburn, A. Lebow (1966)
Rendiconti del Seminario Matematico della Università di Padova
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M. Schechter, Robert Whitley (1988)
Studia Mathematica
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Bruce Barnes (1992)
Studia Mathematica
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Let ℬ be a Banach algebra of bounded linear operators on a Banach space X. If S is a closed operator in X such that (λ - S)^{-1} ∈ ℬ for some number λ, then S is affiliated with ℬ. The object of this paper is to study the spectral theory and Fredholm theory relative to ℬ of an operator which is affiliated with ℬ. Also, applications are given to semigroups of operators which are contained in ℬ.
Živković, Snežana (1997)
Publications de l'Institut Mathématique. Nouvelle Série
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M. Berkani, M. Sarih (2001)
Studia Mathematica
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Let X be a Banach space and let T be a bounded linear operator acting on X. Atkinson's well known theorem says that T is a Fredholm operator if and only if its projection in the algebra L(X)/F₀(X) is invertible, where F₀(X) is the ideal of finite rank operators in the algebra L(X) of bounded linear operators acting on X. In the main result of this paper we establish an Atkinson-type theorem for B-Fredholm operators. More precisely we prove that T is a B-Fredholm operator if and only...
Manuel González, Antonio Martinón (1991)
Extracta Mathematicae
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Let X and Y be infinite dimensional Banach spaces and let L(X,Y) be the class of all (linear continuous) operators acting between X and Y. Mil'man [5] introduced the isometry spectrum I(T) of T ∈ L(X,Y) in the following way: I(T) = {α ≥ 0: ∀ ε > 0, ∃M ∈ S∞(X), ∀x ∈ SM, | ||Tx|| - α | < ε}}, where S∞(X) is the set of all infinite dimensional closed subspaces of X and S...
Jaroslav Zemánek (1984)
Studia Mathematica
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Abdelmoumen, Boulbeba, Baklouti, Hamadi (2009)
Journal of Inequalities and Applications [electronic only]
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Gleason, Jim (2001)
Georgian Mathematical Journal
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