An observation about pseudospectra
نویسندگان
چکیده
For ? > 0 and a bounded linear operator T acting on some Hilbert space, the ?-pseudospectrum of is ??(T) = {z C : ||(zI-T)-1|| ?-1}. This note provides characterization those operators satisfying ?(T) + B(0,?) for all 0. Here |z| < ?}. In particular, such finite dimensional spaces must be normal.
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ژورنال
عنوان ژورنال: Filomat
سال: 2021
ISSN: ['2406-0933', '0354-5180']
DOI: https://doi.org/10.2298/fil2103995j