Results 51 to 60 of about 1,463 (129)
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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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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Preservers of pseudo spectra of operator Jordan triple products
, 2016 Let H be an infinite-dimensional complex Hilbert space and let L (H ) be the algebra of all bounded linear operators on H . For ε > 0 and T ∈ L (H ) , let rε (T ) denote the ε -pseudo spectral radius of T .
M. Bendaoud, A. Benyouness, M. Sarih
semanticscholar +1 more source
Topological properties of the block numerical range of operator matrices
, 2020 We show that the block numerical range of an n×n -operator matrix A corresponding to an operator A on the Banach space X with respect to a decomposition X = ∏Xj has at most n connected components.
Agnes Radl, M. Wolff
semanticscholar +1 more source
Journal of Mathematics, Volume 2025, Issue 1, 2025.This paper investigates an abstract nonhomogeneous backward Cauchy problem governed by an unbounded linear operator in a Hilbert space H. The coefficient operator in the equation is assumed to be unbounded, self‐adjoint, positive, and to possess a discrete spectrum, with data prescribed at the final time t = T.
Nihed Teniou, Xian-Ming Gu
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On some properties of Banach operators
International Journal of Mathematics and Mathematical Sciences, Volume 27, Issue 3, Page 149-153, 2001., 2001 A mapping α from a normed space X into itself is called a Banach operator if there is a constant k such that 0 ≤ k < 1 and ‖α2(x) − α(x)‖ ≤ k‖α(x) − x‖ for all x ∈ X. In this note we study some properties of Banach operators. Among other results we show that if α is a linear Banach operator on a normed space X, then N(α − 1) = N((α−1)2), N(α − 1)∩R(α −
A. B. Thaheem, AbdulRahim Khan
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Exponentials of Bounded Normal Operators
, 2012 The present paper is mainly concerned with equations involving exponentials of bounded normal operators. Conditions implying commutativity of those normal operators are given. This is carried out without the known $2\pi i$-congruence-free hypothesis.
Chaban, Aicha, Mortad, Mohammed Hichem
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Schrödinger operators with potential waveguides on periodic graphs
, 2020 We consider discrete Schrödinger operators with periodic potentials on periodic graphs perturbed by guided positive potentials, which are periodic in some directions and finitely supported in other ones.
O. Post, N. Saburova
semanticscholar +1 more source
On the spectrum of ψ‐contracting operators
International Journal of Stochastic Analysis, Volume 14, Issue 3, Page 303-308, 2001., 2001 The spectrum σ(A) of a continuous linear operator A : E → E defined on a Banach space E, which is contracting with respect to the Hausdorff measure of noncompactness, is investigated.
Anwar A. Al-Nayef
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