A signi? cant sector of the development of spectral theory outside the classical area of
Hilbert space may be found amongst at multipliers de? ned on a complex commutative …

We give a negative answer to the perturbation classes problem: the perturbation class of the
upper semi-Fredholm operators contains properly the strictly singular operators, and the …

We obtain some results for and further examples of subprojective and superprojective
Banach spaces. We also give several conditions providing examples of non-reflexive …

EUDML | Operator semigroups in Banach space theory Skip to main content (access key 's'),
Skip to navigation (access key 'n'), Accessibility information (access key '0') EuDML - The …

It has been an open question for some time whether improjective operators are always
inessential. Here we give some examples that answer in the negative this question as well …

Let SS and SC be the strictly singular and the strictly cosingular operators acting between
Banach spaces, and let P Φ+ and P Φ+ be the perturbation classes for the upper and the …

We study superprojective Banach spaces. We show that they cannot contain copies of ℓ 1,
which restricts the search for non-reflexive examples of these spaces. We also show that the …

We prove that the perturbation class of the upper semi-Fredholm operators from X into Y is
the class of the strictly singular operators, whenever X is separable and Y contains a …

In order to study the inessential operators Tarafdar introduced the notion of improjective
operators. Aiena and González characterize the class of inessential operators in more …

This paper is devoted to study the interrelations between inessential, improjective, strictly
singular and strictly cosingular linear relations. First, we show that the classes of strictly …