TY - Type of reference TI - ε-Pseudo faible-demi-compacité pour les opérateurs matriciels 2 × 2 en block AU - Ines Chtourou AU - Bilel Krichen AB - 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. DO - 10.21494/ISTE.OP.2024.1098 JF - Avancées en Mathématiques Pures et Appliquées KW - Demicompact linear operator, Pseudo-Fredholm, Perturbation theory, Essential pseudo-spectra, Demicompact linear operator, Pseudo-Fredholm, Perturbation theory, Essential pseudo-spectra, L1 - https://www.openscience.fr/IMG/pdf/iste_apam24v15n2_1.pdf LA - fr PB - ISTE OpenScience DA - 2024/03/7 SN - 1869-6090 TT - ε-Pseudo Weak-Demicompactness for 2 × 2 Block Operator Matrices UR - https://www.openscience.fr/%CE%B5-Pseudo-faible-demi-compacite-pour-les-operateurs-matriciels-2-%C3%97-2-en-block IS - Numéro 2 (Spécial CSMT 2023) VL - 15 ER -