Article ID Journal Published Year Pages File Type
4619652 Journal of Mathematical Analysis and Applications 2010 8 Pages PDF
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.

Related Topics
Physical Sciences and Engineering Mathematics Analysis