A NOTE ON THE PERTURBATIONS OF PSEUDOSPECTRA OF 2 × 2 UPPER-TRIANGULAR OPERATOR MATRICES

Marko Kostadinov

DOI Number
https://doi.org/10.22190/FUMI250219051K
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Abstract


In this paper we completely describe the sets ∩C2B(Y;X ) σ"(MC) and ∪C2B(Y;X ) σ"(MC). We also analyze the similarities and differences between these results in the case when the spectrum is perturbed.


Keywords

Hilbert space, operator matrix, 2 × 2 operator matrix, spectrum, pseudospectrum, perturbations of pseudospectrum.

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References


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DOI: https://doi.org/10.22190/FUMI250219051K

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