Abstract
We use the reduced minimum modulus to derive asymptotic formulae for the jumps of the minimum index of a semi-Fredholm operator on a Banach space. The results are then extended to the Riesz eigenvalues greater in absolute value than the essential spectral radius. This reveals a link between the two kinds of singularities.
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Zemanek, J. The reduced minimum modulus and the spectrum. Integr equ oper theory 12, 449–454 (1989). https://doi.org/10.1007/BF01235744
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DOI: https://doi.org/10.1007/BF01235744