Results 31 to 40 of about 1,226 (112)
Spectral inclusions and stability results for strongly continuous semigroups
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 37, Page 2379-2387, 2003., 2003 We prove some spectral inclusions for strongly continuous semigroups. Some stability results are also established.
Abdelkader Elkoutri, Mohamed Aziz Taoudi
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Resolvent convergence of Sturm-Liouville operators with singular potentials
, 2010 In this paper we consider the Sturm-Liuoville operator in the Hilbert space $L_2$ with the singular complex potential of $W^{-1}_2$ and two-point boundary conditions. For this operator we give sufficient conditions for norm resolvent approximation by the
A. M. Savchuk +6 more
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The spectrum of a class of almost periodic operators
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 36, Page 2277-2301, 2003., 2003 For almost Mathieu operators, it is shown that the occurrence of Cantor spectrum and the existence, for every point in the spectrum and suitable phase parameters, of at least one localized eigenfunction which decays exponentially are inconsistent properties.
Norbert Riedel
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On the continuity of spectra for families of magnetic pseudodifferential operators
, 2010 For families of magnetic pseudodifferential operators defined by symbols and magnetic fields depending continuously on a real parameter $\epsilon$, we show that the corresponding family of spectra also varies continuously with $\epsilon$.Comment: 22 ...
Blanchard E. +5 more
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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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A Structured Inverse Spectrum Problem for Infinite Graphs and Unbounded Operators
, 2017 Given an infinite graph $G$ on countably many vertices, and a closed, infinite set $\Lambda$ of real numbers, we prove the existence of an unbounded self-adjoint operator whose graph is $G$ and whose spectrum is $\Lambda$
Khanmohammadi, Ehssan
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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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On a class of $h$-Fourier integral operators
, 2013 In this paper, we study the $L^{2}$-boundedness and $L^{2}$-compactness of a class of $h$-Fourier integral operators. These operators are bounded (respectively compact) if the weight of the amplitude is bounded (respectively tends to $0)$
Abderrahmane, Senoussaoui +1 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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