Results 71 to 80 of about 4,674,369 (143)

The radius of the essential spectrum

Journal of Mathematical Analysis and Applications, 1987
An operator measure s is introduced axiomatically as a map from L(X) (bounded linear operators on the Banach space X into the nonnegative real numbers) which vanishes on all finite rank operators and only on compact operators, is dominated by the norm function and is subadditive and submultiplicative.
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Spectrum, April 1982 [PDF]

, 1982
Volume 4, Number 2 of Spectrum literary journalhttps://nwcommons.nwciowa.edu/spectrum/1007/thumbnail ...
Spectrum Contributors,
core  

The Essential Spectrum of a Sequence of Linear Operators in Banach Spaces

International Journal of Analysis and Applications, 2017
In this work we introduce some essential spectra $(\sigma_{ei}, i=1,...,5)$ of a sequence of closed linear operators $(T_{n})_{n\in\mathbb{N}}$ on Banach space, we prove that if $(T_{n})_{n\in\mathbb{N}}$ converges in the generalized sense to a closed ...
Aymen Ammar, Noui Djaidja, Aref Jeribi
doaj   +2 more sources

Stability of essential approximate point spectrum and essential defect spectrum of linear operator

Filomat, 2015
In the present paper, we use the notion of measure of noncompactness to give some results on Fredholm operators and we establish a fine description of the essential approximate point spectrum and the essential defect spectrum of a closed densely defined linear operator.
Aymen Ammar, Mohammed Dhahri, Aref Jeribi   +2 more
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Spectrum, January 1983 [PDF]

, 1983
Volume 5, Number 1 of Spectrum literary journalhttps://nwcommons.nwciowa.edu/spectrum/1008/thumbnail ...
Spectrum Contributors,
core   +1 more source

Essentially hyponormal operators with essential spectrum contained in a circle

Le Matematiche, 2009
In this paper two results are given . It is proved that if the essential spectrum σ(π(T)) of the bounded hyponormal operator T is contained in a circle, then T is essentially normal operator. Based on this result it is proved that if T∈ L(H) with  ind T =
Shquipe I. Lohaj, Muhib R. Lohaj
doaj  

A New Stability of the S-Essential Spectrum of Multivalued Linear Operators

International Journal of Analysis and Applications, 2017
We unfold in this paper two main results. In the first, we give the necessary assumptions for three linear relations $A$, $B$ and $S$ such that $\sigma_{eap,S}(A+B)= \sigma _{eap,S}(A)$ and $\sigma_{e\delta,S}(A+B)= \sigma_{e\delta,S}(A)$ is true. In the
Aymen Ammar, Slim Fakhfakh, Aref Jeribi
doaj   +2 more sources

Broad-Spectrum Antimicrobial Activity of Thymus Zygis Essential Oil Against Various Microorganisms

Journal of Agricultural Sciences
In this study, the antimicrobial effect of the T. zygis essential oil (EO) was investigated on 68 bacterial and two yeast isolates belonging to 20 different families, including foodborne, ready-to-eat food, aquatic, and collection strains that are ...
Dilek Kahraman Yılmaz
doaj   +1 more source

Hyponormal Operators with Infinite Essential Spectrum [PDF]

Proceedings of the American Mathematical Society, 1975
It is shown that if T T is an essentially hyponormal operator (i.e., the image of
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Essential Self-Adjointness and Invariance of the Essential Spectrum for Dirac Operators

Publications of the Research Institute for Mathematical Sciences, 1982
where «_,(j = 1, 2, 3) and a4 = /? are Hermitian symmetric, constant, 4x4 matrices and satisfy the anti-commutation relations (U) aLjQik + aikaij = 2djkI (/, k = l, 2, 3, 4) (/ is the 4x4 unit matrix). Throughout this paper the potential Q(x) is assumed to be an Hermitian symmetric 4x4 matrix-valued measurable function. The Dirac operator is treated in
Arai, Masaharu, Yamada, Osanobu
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