KHALILI, ZinebAdvisor : HERAIZ, Toufik2023-05-102023-05-102016-06-10http://dspace.univ-msila.dz:8080//xmlui/handle/123456789/37650One of the central questions in the study of the Schechter essential spectrum of closed densely defined linear operator on Banach spaces consists of showing what are the condition that we must impose on such that, for In this field , we gather some results obtained with a detailed treatment of Schechter essential spectrum of closed densely defined linear operator subjected to additive perturbation such that or belonging to arbitrary subsets of contained in the ideal of Fredhom perturbationsenEssential spectra, Fredholm perturbation, Transport equationThesis