Several operational quantities have appeared in the literature characterizing upper semi-Fredholm operators. Here we show that these quantities can be divided into three classes, in such a way that two of them are equivalent if they belong to the same class, and are comparable and not equivalent if they belong to different classes. Moreover, we give a similar classification for operational quantities characterizing lower semi-Fredholm operators.
@article{bwmeta1.element.bwnjournal-article-smv114i1p13bwm,
author = {Manuel Gonz\'alez and Antonio Martin\'on},
title = {Operational quantities characterizing semi-Fredholm operators},
journal = {Studia Mathematica},
volume = {113},
year = {1995},
pages = {13-27},
zbl = {0830.47008},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-smv114i1p13bwm}
}
González, Manuel; Martinón, Antonio. Operational quantities characterizing semi-Fredholm operators. Studia Mathematica, Tome 113 (1995) pp. 13-27. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-smv114i1p13bwm/
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