Some Remarks on Perturbation Classes of Semi-Fredholm and Fredholm Operators

نویسندگان

  • Abdelkader Dehici
  • Khaled Saoudi
چکیده

We show the existence of Banach spaces X, Y such that the set of strictly singular operators ᏿(X,Y) (resp., the set of strictly cosingular operators Ꮿ᏿(X,Y)) would be strictly included in F + (X,Y) (resp., F − (X,Y)) for the nonempty class of closed densely defined upper semi-Fredholm operators Φ + (X,Y) (resp., for the nonempty class of closed densely defined lower semi-Fredholm operators Φ − (X,Y)). This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution , and reproduction in any medium, provided the original work is properly cited.

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عنوان ژورنال:
  • Int. J. Math. Mathematical Sciences

دوره 2007  شماره 

صفحات  -

تاریخ انتشار 2007