In this article, poles, isolated spectral points, group, Drazin and Koliha-Drazin invertible
elements in the context of quotient Banach algebras or in ranges of (not necessarily …

Abstract Generalized Weyl operators on Hilbert spaces have been introduced and studied
by Djordjević (Proc Am Math Soc, 130: 81–ll4, 2001). In this paper, we provide a …

This paper is an attempt to give an axiomatic approach to the investigation of various kinds
of generalizations of Drazin invertibility in Banach algebras. We shall say that an element a …

We determine the perturbation classes of Fredholm and Weyl elements, as well the
“commuting perturbation classes” of Fredholm, Weyl and Browder elements with respect to …

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This paper illustrates some initial steps taken in the effort of unifying the theory of positivity in
ordered Banach algebas (OBAs) with the general Fredholm theory in Banach algebras. We …

SpringerBriefs in Mathematics showcases expositions in all areas of mathematics and
applied mathematics. Manuscripts presenting new results or a single new result in a …

In this paper, we give another definition of Ruston elements and almost Ruston elements,
which is equivalent to the definitions given by Mouton and Raubenheimer in the case that …

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By considering arbitrary mappings ω from a Banach algebra A into the set of all nonempty,
compact subsets of the complex plane such that for all a∈ A, the set ω (a) lies between the …