Spectral properties for polynomial and matrix operators involving demicompactness classes
| Autor: | Fatma Ben Brahim, Aref Jeribi, Bilel Krichen |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Extracta Mathematicae, Vol 33, Iss 1 (2018) |
| Druh dokumentu: | article |
| ISSN: | 0213-8743 2605-5686 |
| Popis: | The first aim of this paper is to show that a polynomially demicompact operator satisfying certain conditions is demicompact. Furthermore, we give a refinement of the Schmoëger and the Rakocević essential spectra of a closed linear operator involving the class of demicompact ones. The second aim of this work is devoted to provide some sufficient conditions on the inputs of a closable block operator matrix to ensure the demicompactness of its closure. An example involving the Caputo derivative of fractional of order α is provided. Moreover, a study of the essential spectra and an investigation of some perturbation results. |
| Databáze: | Directory of Open Access Journals |
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