Journal of University of Chinese Academy of Sciences >
Judgement on stability of Weyl’s theorem for the upper triangular operator matrices
Received date: 2012-07-06
Revised date: 2012-10-31
Online published: 2013-09-15
An operator T is said to satisfy a-Browder's theorem if σa(T)\σea(T)???π00a(T), where σa(T) and σea(T) denote the approximate point spectrum and the essential approximate point spectrum, respectively, and π00a(T)={λ∈isoσa(T),0< dimN(T-λI)<∞}. If σa(T)\σea(T)=π00a(T), we say that T satisfies a-Weyl's theorem. In this note, by using the characteristics of semi-Fredholm domain of the diagonal of the upper triangular operator matrix, we investigate the stability of a-Browder's theorem and a-Weyl's theorem for the upper triangular operator matrices under compact perturbations.
YIN Jun-Qiang , CAO Xiao-Hong . Judgement on stability of Weyl’s theorem for the upper triangular operator matrices[J]. Journal of University of Chinese Academy of Sciences, 2013 , 30(5) : 591 -597 . DOI: 10.7523/j.issn.2095-6134.2013.05.003
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