Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4619652 | Journal of Mathematical Analysis and Applications | 2010 | 8 Pages |
Abstract
We prove that certain operational quantities q which characterize upper-semi Fredholm operators are supermultiplicative, in the sense of that q(S)q(T)⩽q(ST). Based on the distortion of Banach spaces we show that another is not supermultiplicative. Moreover we introduce two supermultiplicative operational quantities which characterize also the upper-semi Fredholm operators and we prove that they are not equivalent to some operational quantities known.
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