Abstract
We show that the perturbation class for the upper semi-Fredholm operators between two Banach spaces X and Y coincides with the strictly singular operators when X is subprojective and that the perturbation class for the lower semi-Fredholm operators coincides with the strictly cosingular operators when Y is superprojective. Similar results were previously obtained under stronger conditions for X and Y.
Original language | English (US) |
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Article number | 124191 |
Journal | Journal of Mathematical Analysis and Applications |
Volume | 489 |
Issue number | 2 |
DOIs | |
State | Published - Sep 15 2020 |
All Science Journal Classification (ASJC) codes
- Analysis
- Applied Mathematics