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arXiv · 1906.10609

On operators with closed range and semi-Fredholm operators over W*-algebras

Stefan Ivkovic
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Abstract

In this paper we consider A-Fredholm and semi-A-Fredholm operators on Hilbert C*-modules over a W*-algebra A defined in [3],[10]. Using the assumption that A is a W*-algebra (and not an arbitrary C*-algebra), we obtain several results such as generalization of Schechter-Lebow characterization of semi-Fredholm operators and generalization of "punctured neighbourhood" theorem, as well as some other results that generalize their classical counterparts. We consider both adjointable and non adjointable semi-Fredholm operators over W*-algebras. Moreover, we also work with general bounded, adjointable operators with closed range over C*-algebras and prove a generalization to Hilbert C*-modules of the result in [1] on Hilbert spaces.

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Stefan Ivkovic. 2019-06-25. On operators with closed range and semi-Fredholm operators over W*-algebras. https://doi.org/10.1134/s1061920820010057

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