Displaying similar documents to “The spectra of general differential operators in the direct sum spaces”

Spectral analysis for rank one perturbations of diagonal operators in non-archimedean Hilbert space

Toka Diagana, George D. McNeal (2009)

Commentationes Mathematicae Universitatis Carolinae

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The paper is concerned with the spectral analysis for the class of linear operators A = D λ + X Y in non-archimedean Hilbert space, where D λ is a diagonal operator and X Y is a rank one operator. The results of this paper turn out to be a generalization of those results obtained by Diarra.

On the localization of the spectrum for quasi-selfadjoint extensions of a Carleman operator

S. M. Bahri (2012)

Mathematica Bohemica

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In the present work, using a formula describing all scalar spectral functions of a Carleman operator A of defect indices ( 1 , 1 ) in the Hilbert space L 2 ( X , μ ) that we obtained in a previous paper, we derive certain results concerning the localization of the spectrum of quasi-selfadjoint extensions of the operator A .

Isolated points of spectrum of k-quasi-*-class A operators

Salah Mecheri (2012)

Studia Mathematica

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Let T be a bounded linear operator on a complex Hilbert space H. In this paper we introduce a new class, denoted *, of operators satisfying T * k ( | T ² | - | T * | ² ) T k 0 where k is a natural number, and we prove basic structural properties of these operators. Using these results, we also show that if E is the Riesz idempotent for a non-zero isolated point μ of the spectrum of T ∈ *, then E is self-adjoint and EH = ker(T-μ) = ker(T-μ)*. Some spectral properties are also presented.