Results 41 to 50 of about 332 (118)
On the essential spectra of unbounded operator matrices with non diagonal domain and an application
Operators and Matrices, 2019 This paper is devoted to the investigation of the spectral stability of unbounded operator matrices with non diagonal domain in product of Banach spaces.
Marwa Belghith, N. Moalla, I. Walha
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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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Open Mathematics, 2020 In this paper, we describe a method to solve the problem of finding periodic solutions for second-order neutral delay-differential equations with piecewise constant arguments of the form x″(t) + px″(t − 1) = qx([t]) + f(t), where [⋅] denotes the greatest
I. Muminov Mukhiddin, H. M. Murid Ali
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Common fixed point theorems for a pair of countably condensing mappings in ordered banach spaces
International Journal of Stochastic Analysis, Volume 16, Issue 3, Page 243-248, 2003., 2003 In this paper some common fixed point theorems for a pair of multivalued weakly isotone mappings on an ordered Banach space are proved.
B. C. Dhage +2 more
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The Property (EA) and Local Spectral Theory
International Journal of Mathematics and Mathematical Sciences, Volume 2025, Issue 1, 2025.In this paper, we introduce and study the spectral property (EA). This property means that the difference between the approximate point spectrum and the upper semi‐Fredholm spectrum coincides with the difference between the approximate point spectrum and the upper semi‐Weyl spectrum.
Elvis Aponte +3 more
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Spectral integration and spectral theory for non‐Archimedean Banach spaces
International Journal of Mathematics and Mathematical Sciences, Volume 31, Issue 7, Page 421-442, 2002., 2002 Banach algebras over arbitrary complete non‐Archimedean fields are considered such that operators may be nonanalytic. There are different types of Banach spaces over non‐Archimedean fields. We have determined the spectrum of some closed commutative subalgebras of the Banach algebra ℒ(E) of the continuous linear operators on a free Banach space E ...
S. Ludkovsky, B. Diarra
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On unbounded commuting Jacobi operators and some related issues
Concrete Operators, 2019 We consider the situations, when two unbounded operators generated by infinite Jacobi matrices, are self-adjoint and commute. It is found that if two Jacobi matrices formally commute, then two corresponding operators are either self-adjoint and commute ...
Osipov Andrey
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International Journal of Mathematics and Mathematical Sciences, Volume 2025, Issue 1, 2025.For the Weinstein Laplacian considered on the Hilbert space which makes it a self‐adjoint operator, the Von Neumann spectral decomposition is given. As applications, a new integral representation for the Weinstein heat kernel is given. Also, it is proved that the spectrum of the semigroup associated with the Weinstein Laplacian is reduced to its ...
Abdelilah El Mourni +3 more
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Continuity and general perturbation of the Drazin inverse for closed linear operators
Abstract and Applied Analysis, Volume 7, Issue 6, Page 335-347, 2002., 2002 We study perturbations and continuity of the Drazin inverse of a closed linear operator A and obtain explicit error estimates in terms of the gap between closed operators and the gap between ranges and nullspaces of operators. The results are used to derive a theorem on the continuity of the Drazin inverse for closed operators and to describe the ...
N. Castro González +2 more
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Nonlocal heat equations with generalized fractional Laplacian
Advances in Nonlinear AnalysisWe study heat equations with generalized fractional Laplacian, which is defined by the spectral theory. Here we develop the existence theory for those equations. Also, we present some numerical simulations for our problems.
Kossowski Igor, Przeradzki Bogdan
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