Articles

ESSENTIAL APPROXIMATE POINT SPECTRA FOR UPPER TRIANGULAR MATRIX OF LINEAR RELATIONS

  • Souhir ELLEUCH ,
  • Maher MNIF
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  • D´epartement de Math´ematiques, Universit´e de Sfax, Facult´e des Sciences de Sfax, Laboratoire de Physiques Math´ematiques, B.P. 1171, 3000 Sfax, Tunisie

Received date: 2011-06-09

  Revised date: 2012-02-14

  Online published: 2013-07-20

Abstract

When LR(H) and B ∈ LR(K) are given, for C ∈ LR(K, H) we denote by MC the linear relation acting on the infinite dimensional separable Hilbert space HKof the form MC =

(A  C ).                                                                                                            

0   B
In this paper, we give the necessary and sufficient conditions on A and B for which MC is upper semi-Fredholm with negative index or Weyl for some C ∈ LR(K, H).

Cite this article

Souhir ELLEUCH , Maher MNIF . ESSENTIAL APPROXIMATE POINT SPECTRA FOR UPPER TRIANGULAR MATRIX OF LINEAR RELATIONS[J]. Acta mathematica scientia, Series B, 2013 , 33(4) : 1187 -1201 . DOI: 10.1016/S0252-9602(13)60073-9

References

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[4] Cao X H, Meng B. Essential approximate point spectra and Weyl´s theorem for operator matrices. J Math Anal Appl, 2005, 304: 759–771

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