Opuscula Mathematica
Opuscula Math. 41, no. 3 (2021), 395-412

Spectrum localization of a perturbed operator in a strip and applications

Michael Gil'
Abstract. Let \(A\) and \(\tilde{A}\) be bounded operators in a Hilbert space. We consider the following problem: let the spectrum of \(A\) lie in some strip. In what strip the spectrum of \(\tilde{A}\) lies if \(A\) and \(\tilde{A}\) are "close"? Applications of the obtained results to integral operators and matrices are also discussed. In addition, we apply our perturbation results to approximate the spectral strip of a Hilbert-Schmidt operator by the spectral strips of finite matrices.
Keywords: operator, spectrum, perturbation, approximation, integral operator, matrix.
Mathematics Subject Classification: 47A10, 47A55, 47B10.
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About the authors ▼
Michael Gil'
https://orcid.org/0000-0002-6404-9618
Department of Mathematics, Ben Gurion University of the Negev, P.0. Box 653, Beer-Sheva 84105, Israel
About the article ▼
Communicated by P.A. Cojuhari.
Received: 2020-12-24.
Accepted: 2021-01-24.
Published online: 2021-04-19.
Cite this article as ▼
Michael Gil', Spectrum localization of a perturbed operator in a strip and applications, Opuscula Math. 41, no. 3 (2021), 395-412, https://doi.org/10.7494/OpMath.2021.41.3.395.
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