Fredholm theory for demicompact linear relations


  • Aymen Ammar University of Sfax
  • Slim Fakhfakh University of Sfax
  • Aref Jeribi University of Sfax



demicompact linear relations, Fredholm theory, block matrix


We first attempt to determine conditions on a linear relation T such that μT becomes a demicompact linear relation for each μ ∈ [0,1)(see Theorems 2.4 and 2.5). Second, we display some results on Fredholm and upper semi-Fredholm linear relations involving a demicompact one(see Theorems 3.1 and 3.2). Finally, we provide some results in which a block matrix of linear relations becomes a demicompact block matrix of linear relations (see Theorems 4.2 and 4.3).


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Author Biographies

Aymen Ammar, University of Sfax

Department of mathematics, Faculty of Sciences of Sfax

Slim Fakhfakh, University of Sfax

Department of Mathematics, Faculty of Sciences of Sfax

Aref Jeribi, University of Sfax

Department of Mathematics, Faculty of Sciences of Sfax


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How to Cite

A. Ammar, S. Fakhfakh, and A. Jeribi, “Fredholm theory for demicompact linear relations”, Appl. Gen. Topol., vol. 23, no. 2, pp. 425–436, Oct. 2022.



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