Abstract
In this paper we define and study operators of Saphar type in a Banach space, their subclasses, essentially left (right) Drazin invertible operators and left (right) Weyl–Drazin invertible operators, by means of kernels and ranges of powers of an operator. A bounded linear operator T on a Banach space X is said to be of Saphar type if T is a direct sum of a Saphar operator and a nilpotent one. We prove that T is essentially left (right) Drazin invertible if and only if T is a direct sum of a left (right) Fredholm operator and a nilpotent one, as well as that T is left (right) Weyl–Drazin invertible if and only if T is a direct sum of a left (right) Weyl operator and a nilpotent operator. We also consider the corresponding spectra.
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Živković-Zlatanović, S.Č., Djordjević, S.V. On some classes of Saphar type operators. Rev. Real Acad. Cienc. Exactas Fis. Nat. Ser. A-Mat. 116, 170 (2022). https://doi.org/10.1007/s13398-022-01314-5
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DOI: https://doi.org/10.1007/s13398-022-01314-5
Keywords
- Banach space
- Quasi–Fredholm operators
- Saphar operators
- Left and right Fredholm operators
- Left and right Weyl operators
- Left and right Drazin invertible operators
- Spectrum