Central European Journal of Mathematics

, Volume 5, Issue 2, pp 335–344 | Cite as

Limit points of eigenvalues of truncated unbounded tridiagonal operators

  • E.K. Ifantis
  • C.G. Kokologiannaki
  • E. Petropoulou
Research Article


Let T be a self-adjoint tridiagonal operator in a Hilbert space H with the orthonormal basis {en}n=1, σ(T) be the spectrum of T and Λ(T) be the set of all the limit points of eigenvalues of the truncated operator TN. We give sufficient conditions such that the spectrum of T is discrete and σ(T) = Λ(T) and we connect this problem with an old problem in analysis.


Tridiagonal operators spectrum limit points of eigenvalues orthogonal polynomials continued fractions 

MSC (2000)

47A10 40A15 42C05 


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Copyright information

© Versita Warsaw and Springer-Verlag Berlin Heidelberg 2007

Authors and Affiliations

  • E.K. Ifantis
    • 1
  • C.G. Kokologiannaki
    • 1
  • E. Petropoulou
    • 1
  1. 1.Department of MathematicsUniversity of PatrasPatrasGreece

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