Communications of the Korean Mathematical Society (대한수학회논문집)

Korean Mathematical Society (대한수학회)
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SOME FREDHOLM THEORY RESULTS AROUND RELATIVE DEMICOMPACTNESS CONCEPT

  • Chaker, Wajdi (Department of New Economy University of Sfax Higher Institute of Comercial Studies of Sfax) ;
  • Jeribi, Aref (Department of Mathematics University of Sfax Faculty of Sciences of Sfax) ;
  • Krichen, Bilel (Department of Mathematics University of Sfax Faculty of Sciences of Sfax)
  • Received : 2020.06.25
  • Accepted : 2020.11.19
  • Published : 2021.04.30
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Abstract

In this paper, we provide a characterization of upper semi-Fredholm operators via the relative demicompactness concept. The obtained results are used to investigate the stability of various essential spectra of closed linear operators under perturbations belonging to classes involving demicompact, as well as, relative demicompact operators.

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References

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