Titre : ε-Pseudo faible-demi-compacité pour les opérateurs matriciels 2 × 2 en block 

Auteurs : Ines Chtourou
, Bilel Krichen,  

Revue : Avancées en Mathématiques Pures et Appliquées 

Numéro : Numéro 2 (Spécial CSMT 2023) 

Volume : 15 

Date : 2024/03/7 

DOI : 10.21494/ISTE.OP.2024.1098 

ISSN : 1869-6090 

Résumé : The purpose of this paper is to give some properties for the so-called ε-pseudo weakly demicompact linear operators acting on Banach spaces. Some sufficient conditions on the entries of an unbounded 2 × 2 block operator matrix $$$\mathcal{L}_{0}$$$ ensuring its ε-pseudo weak demicompactness are provided. In addition, we develop, in the bounded case, the class of ε-pseudo Fredholm perturbation to investigate the essential pseudo-spectra of $$$\mathcal{L}_{0}$$$. The results are formulated in terms of some denseness conditions on the topological dual space. 

Éditeur : ISTE OpenScience