Results 41 to 50 of about 142 (138)

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
wiley   +1 more source

Negative Powers of Contractions Having a Strong AA+ Spectrum

Moroccan Journal of Pure and Applied Analysis, 2023
Zarrabi proved in 1993 that if the spectrum of a contraction T on a Banach space is a countable subset of the unit circle 𝕋, and if limn→+∞log(‖T−n‖)n=0{\lim _{n \to + \infty }}{{\log \left( {\left\| {{T^{ - n}}} \right\|} \right)} \over {\sqrt n ...
Esterle Jean
doaj   +1 more source

Spectral Decomposition of the Weinstein Laplacian and Its Application to the Associated Heat Transform

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, Nour Eddine Askour, Imane El Yazidi, Muhammad Ahsan   +3 more
wiley   +1 more source

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, J. J. Koliha, V. Rakočević   +2 more
wiley   +1 more source

Taylor Spectrum and Characteristic Functions of Commuting 2-Contractions [PDF]

, 2008
2000 Mathematics Subject Classification: 47A10, 47A13.In this paper, we give a description of Taylor spectrum of commuting 2-contractions in terms of characteritic functions of such contractions. The case of a single contraction obtained by B. Sz.
Bendoukha, Berrabah
core  

A self adjoint expansion of a symmetric differential operator with operator coefficient

, 2007
In this work, we prove that the closure of a symmetric operator L0which is formed by differential expression(L0y)(x) = −(p(x)y(x)) − Q(x)y(x)and with the boundary conditioncos α.y(0) + sinα.y(0) = 0is self adjoint where α ∈ (−∞,∞) in the space L2(0,∞; H )
Adıgüzelov, Ehliman, Karayel, Serpil
core   +1 more source

A Modified Regularization Method for Inverse Problems of Nonhomogeneous Differential Operator Equation

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
wiley   +1 more source

On the generalized Kato spectrum [PDF]

, 2011
2010 Mathematics Subject Classification: 47A10.We show that the symmetric difference between the generalized Kato spectrum and the essential spectrum defined in [7] by sec(T) = {l О C ; R(lI-T) is not closed } is at most countable and we also give some
Messirdi, Bekkai, Benharrat, Mohammed
core  

An introduction to the distorted Fourier transform

Advanced Nonlinear Studies
This article is intended as an introduction to the distorted Fourier transform associated with a Schrödinger operator on the line or the half-line. This versatile tool has seen numerous applications in nonlinear PDE in recent years.
Ko Haram, Schlag Wilhelm
doaj   +1 more source

Certain properties of the essential spectra in Banach spaces [PDF]

, 2017
Paper presented at the 4th Strathmore International Mathematics Conference (SIMC 2017), 19 - 23 June 2017, Strathmore University, Nairobi, Kenya.Let X be an arbitrary Banach space, and L (X) be the set of all bounded linear operators on X.
Agure, J. O., Muhati, L. N., Bonyo, J. O.   +2 more
core   +1 more source