@ARTICLE{10.21494/ISTE.OP.2024.1098, 

TITLE={ε-Pseudo Weak-Demicompactness for 2 × 2 Block Operator Matrices}, 
  
AUTHOR={Ines Chtourou
, Bilel Krichen, }, 
	
JOURNAL={Advances in Pure and Applied Mathematics}, 
	
VOLUME={15}, 

NUMBER={Issue 2 (Special CSMT 2023)}, 
	
YEAR={2024}, 

URL={http://openscience.fr/%CE%B5-Pseudo-Weak-Demicompactness-for-2-%C3%97-2-Block-Operator-Matrices}, 
	
DOI={10.21494/ISTE.OP.2024.1098}, 
	
ISSN={1869-6090}, 
	
ABSTRACT={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.}}