Results 11 to 20 of about 100 (42)
On the solutions of nonlinear initial‐boundary value problems
Abstract and Applied Analysis, Volume 2004, Issue 5, Page 407-424, 2004., 2004 We deal with the general initial‐boundary value problem for a second‐order nonlinear nonstationary evolution equation. The associated operator equation is studied by the Fredholm and Nemitskii operatortheory. Under local Hölder conditions for the nonlinear member, we observe quantitative and qualitative properties of the set of solutions of the given ...
Vladimír Ďurikovič +1 more
wiley +1 more source
α-Fredholm operators relative to invariant subspaces
Operators and Matrices, 2019 Let T be a bounded linear operator on a Hilbert space H and let W be a closed T− invariant subspace of H . Then T has a matrix representation on the space W ⊕W⊥ by T = [ A C 0 B ] .
Salvador Sánchez-Perales +2 more
semanticscholar +1 more source
Block Toeplitz operators with frequency‐modulated semi‐almost periodic symbols
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 34, Page 2157-2176, 2003., 2003 This paper is concerned with the influence of frequency modulation on the semi‐Fredholm properties of Toeplitz operators with oscillating matrix symbols. The main results give conditions on an orientation‐preserving homeomorphism α of the real line that ensure the following: if b belongs to a certain class of oscillating matrix functions (periodic ...
A. Böttcher, S. Grudsky, I. Spitkovsky
wiley +1 more source
Some results on dominant operators
International Journal of Mathematics and Mathematical Sciences, Volume 21, Issue 2, Page 217-220, 1998., 1997 We show that the Weyl spectrum of a dominant operator satisfies the spectral mapping theorem for analytic functions and then answer a question of Oberai.
Youngoh Yang
wiley +1 more source
A Note on Property $(gb)$ and Perturbations [PDF]
, 2012 An operator T ∈ B(X) defined on a Banach space X satisfies property (gb) if the complement in the approximate point spectruma(T) of the upper semi-B-Weyl spectrumSBF + (T) coincides with the set (T) of all poles of the resolvent of T.
Qingping Zeng, H. Zhong
semanticscholar +1 more source
Zoochoric and hydrochoric maritime dispersal of the Opuntia monacantha (Willd.) Haw. (Cactaceae) [PDF]
Biotemas, 2012 Evolutionary adaptations in the morphology and physiology of cactus species have been associated to their mechanisms of dispersal and colonization. The dispersal mechanisms and modes of Opuntia monacantha (Willd.) Haw.
Angelo Martins Fraga +4 more
doaj
ᵀ2^*-algebras of Bergman type operators with continuous coefficients on polygonal domains
, 2015 Given α ∈ (0,2] , the C∗ -algebra AKα generated by the identity operator and by the Bergman and anti-Bergman projections acting on the Lebesgue space L(Kα) over the open sector Kα = { z = reiθ : r > 0, θ ∈ (0,πα) is studied.
Y. Karlovich
semanticscholar +1 more source
Generalized weyl's theorem for algebraically quasi-paranormal operators
Journal of Inequalities and Applications, 2012 Let T or T* be an algebraically quasi-paranormal operator acting on a Hilbert space. We prove: (i) generalized Weyl's theorem holds for f(T) for every f ∈ H(σ (T)); (ii) generalized a-Browder's theorem holds for f(S) for every S ≺ T and f ∈ H(σ(S)); (iii)
I. An, Y. Han
semanticscholar +2 more sources
A transmission problem for the Helmholtz equation with higher order boundary conditions
, 2015 The present paper deals with some properties for certain classes of Wiener-Hopf operators associated with a wave diffraction problem. This diffraction problem is mathematically modeled by the Helmholtz equation and higher order boundary conditions on an ...
Alberto Simões
semanticscholar +1 more source
Weyl's Theorem for Class A Operators
, 2001 In this paper, we show that Weyl’s theorem holds for class A operators under a certain condition. We also show that a class A operator whose Weyl spectrum equals to the one-point set {0} is always compact and normal.
A. Uchiyama
semanticscholar +1 more source