A bounded linear operator T on a complex Banach space X is called an operator of Saphar type if its kernel is contained in its generalized range and T is relatively regular. For T of Saphar type we determine the supremum of all positive numbers δ such that T - λI is of Saphar type for |λ| < δ.
@article{bwmeta1.element.bwnjournal-article-smv113i2p169bwm,
author = {Christoph Schmoeger},
title = {The stability radius of an operator of Saphar type},
journal = {Studia Mathematica},
volume = {113},
year = {1995},
pages = {169-175},
zbl = {0819.47002},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-smv113i2p169bwm}
}
Schmoeger, Christoph. The stability radius of an operator of Saphar type. Studia Mathematica, Tome 113 (1995) pp. 169-175. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-smv113i2p169bwm/
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