Results 11 to 20 of about 396 (56)
On new strong versions of Browder type theorems
Open Mathematics, 2018 An operator T acting on a Banach space X satisfies the property (UWΠ) if σa(T)∖ σSF+−$\begin{array}{} \sigma_{SF_{+}^{-}} \end{array} $(T) = Π(T), where σa(T) is the approximate point spectrum of T, σSF+−$\begin{array}{} \sigma_{SF_{+}^{-}} \end{array} $
Sanabria José +4 more
doaj +1 more source
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
semanticscholar +1 more source
On bifurcation for semilinear elliptic Dirichlet problems and the Morse-Smale index theorem [PDF]
, 2013 We study bifurcation from a branch of trivial solutions of semilinear elliptic Dirichlet boundary value problems on star-shaped domains, where the bifurcation parameter is introduced by shrinking the domain.
Alessandro Portaluri +8 more
core +2 more sources
On the closed range problem for composition operators on the Dirichlet space
Concrete Operators, 2019 We characterize closed range composition operators on the Dirichlet space for a particular class of composition symbols. The characterization relies on a result about Fredholm Toeplitz operators with BMO1 symbols, and with Berezin transforms of vanishing
Zorboska Nina
doaj +1 more source
A unifying approach to Weyl type theorems for Banach space operators [PDF]
, 2013 Weyl type theorems have been proved for a considerably large number of classes of operators. In this paper, by introducing the class of quasi totally hereditarily normaloid operators, we obtain a theoretical and general framework from which Weyl type ...
AIENA, Pietro, Guillen Jesus, Pena Pedro
core +1 more source
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
On the spectral mapping theorem for essential spectra [PDF]
, 1985 B. Gramsch and D. Lay have studied spectral mapping theorems for the essential spectra of an operator acting in a complex Banach space. Firstly they consider operators belonging to the Banach algebra of all bounded linear operators on the space, and ...
González Ortiz, Manuel José +1 more
core +2 more sources
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