Abstract
We prove an asymptotic formula for the stability radius of a semi-Fredholm operator on a Banach space in terms of the reduced minimum modulus. In particular, this gives a new proof of the Fredholm case studied by Förster and Kaashoek [4].
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Zemánek, J. The stability radius of a semi-Fredholm operator. Integr equ oper theory 8, 137–144 (1985). https://doi.org/10.1007/BF01199985
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DOI: https://doi.org/10.1007/BF01199985