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Displaying 201 – 220 of 700

Limit points of eigenvalues of truncated unbounded tridiagonal operators

E.K. Ifantis, C.G. Kokologiannaki, E. Petropoulou (2007)

Open Mathematics

Let T be a self-adjoint tridiagonal operator in a Hilbert space H with the orthonormal basis {e n}n=1∞, σ(T) be the spectrum of T and Λ(T) be the set of all the limit points of eigenvalues of the truncated operator T N. We give sufficient conditions such that the spectrum of T is discrete and σ(T) = Λ(T) and we connect this problem with an old problem in analysis.

Linear maps on Mₙ(ℂ) preserving the local spectral radius

Abdellatif Bourhim, Vivien G. Miller (2008)

Studia Mathematica

Let x₀ be a nonzero vector in ℂⁿ. We show that a linear map Φ: Mₙ(ℂ) → Mₙ(ℂ) preserves the local spectral radius at x₀ if and only if there is α ∈ ℂ of modulus one and an invertible matrix A ∈ Mₙ(ℂ) such that Ax₀ = x₀ and $Φ (T) = α A T A^{- 1}$ for all T ∈ Mₙ(ℂ).

Linear maps preserving the generalized spectrum.

Mostafa Mbekhta (2007)

Extracta Mathematicae

Let H be an infinite-dimensional separable complex Hilbert space and B(H) the algebra of all bounded linear operators on H. For an operator T in B(H), let σg(T) denote the generalized spectrum of T. In this paper, we prove that if φ: B(H) → B(H) is a surjective linear map, then φ preserves the generalized spectrum (i.e. σg(φ(T)) = σg(T) for every T ∈ B(H)) if and only if there is A ∈ B(H) invertible such that either φ(T) = ATA-1 for every T ∈ B(H), or φ(T) = ATtrA-1 for every T ∈ B(H). Also, we...

Linear operators as measure preserving transformations

Elias Flytzanis (1977)

Annales scientifiques de l'Université de Clermont. Mathématiques

Local behaviour of the polynomial calculus of operators.

V. Müller (1992)

Journal für die reine und angewandte Mathematik

Local entropy moduli and eigenvalues of operators in Banach spaces.

Bernd Carl, Thomas Kühn (1985)

Revista Matemática Iberoamericana

In the paper local entropy moduli of operators between Banach spaces are introduced. They constitue a generalization of entropy numbers and moduli, and localize these notions in an appropriate way. Many results regarding entropy numbers and moduli can be carried over to local entropy moduli. We investigate relations between local entropy moduli and s-numbers, spectral properties, eigenvalues, absolutely summing operators. As applications, local entropy moduli of identical and diagonal operators...

Local ergodic theorems.

Teresa Bermúdez, Manuel González, Mostafa Mbekhta (1998)

Extracta Mathematicae

Local spectral radius formula for operators in Banach spaces

Vladimír Müller (1988)

Czechoslovak Mathematical Journal

Local spectral theory for $2 \times 2$ operator matrices.

Elbjaoui, H., Zerouali, E. H. (2003)

International Journal of Mathematics and Mathematical Sciences

Locally spectrally bounded linear maps

M. Bendaoud, M. Sarih (2011)

Mathematica Bohemica

Let $ℒ (ℋ)$ be the algebra of all bounded linear operators on a complex Hilbert space $ℋ$ . We characterize locally spectrally bounded linear maps from $ℒ (ℋ)$ onto itself. As a consequence, we describe linear maps from $ℒ (ℋ)$ onto itself that compress the local spectrum.

Lower bounds for eigenvalues of Schatten-von Neumann operators.

Gil, M.I. (2007)

JIPAM. Journal of Inequalities in Pure & Applied Mathematics [electronic only]

Lp-essential Spectral Theory of Ordinary Differential Operators With Almost Constant Coefficients

Valeri A. Erovenko (1997)

Matematički Vesnik

Maps on matrices that preserve the spectral radius distance

Rajendra Bhatia, Peter Šemrl, A. Sourour (1999)

Studia Mathematica

Let ϕ be a surjective map on the space of n×n complex matrices such that r(ϕ(A)-ϕ(B))=r(A-B) for all A,B, where r(X) is the spectral radius of X. We show that ϕ must be a composition of five types of maps: translation, multiplication by a scalar of modulus one, complex conjugation, taking transpose and (simultaneous) similarity. In particular, ϕ is real linear up to a translation.

Currently displaying 201 – 220 of 700

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Displaying 201 – 220 of 700

Limit points of eigenvalues of truncated unbounded tridiagonal operators

Linear maps on Mₙ(ℂ) preserving the local spectral radius

Linear maps preserving the generalized spectrum.

Linear operators as measure preserving transformations

Local behaviour of the polynomial calculus of operators.

Local entropy moduli and eigenvalues of operators in Banach spaces.

Local ergodic theorems.

Local spectral radius formula for operators in Banach spaces

Local spectral theory for $2 \times 2$ operator matrices.

Locally spectrally bounded linear maps

Lower bounds for eigenvalues of Schatten-von Neumann operators.

Lp-essential Spectral Theory of Ordinary Differential Operators With Almost Constant Coefficients

Maps on matrices that preserve the spectral radius distance

Mathematical analysis of electromagnetic open Waveguides

Measures of Non-strict-singularity and Non-strict-cosingularity

Method of orthogonal projections and approximation of the spectrum of a bounded operator II

Method of orthogonal projections and approximation of the spectrum of a bounded operator

Minimalflächen mit polygonalem Rand.

Minimaxprinzipe zur Bestimmung der Eigenwerte J-nichtnegativer Operatoren.

Möbius transformations and monogenic functional calculus.

Currently displaying 201 – 220 of 700