Weyl's theorem for algebraically k-quasiclass A operators
Author(s) -
Fugen Gao,
Xiaochun Fang
Publication year - 2012
Publication title -
opuscula mathematica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.481
H-Index - 16
eISSN - 2300-6919
pISSN - 1232-9274
DOI - 10.7494/opmath.2012.32.1.125
Subject(s) - mathematics , operator (biology) , spectrum (functional analysis) , hilbert space , rank (graph theory) , algebraically closed field , integer (computer science) , separable space , pure mathematics , discrete mathematics , combinatorics , mathematical analysis , physics , quantum mechanics , biochemistry , chemistry , repressor , computer science , transcription factor , gene , programming language
If \(T\) or \(T^*\) is an algebraically \(k\)-quasiclass \(A\) operator acting on an infinite dimensional separable Hilbert space and \(F\) is an operator commuting with \(T\), and there exists a positive integer \(n\) such that \(F^n\) has a finite rank, then we prove that Weyl's theorem holds for \(f(T)+F\) for every \(f \in H(\sigma(T))\), where \(H(\sigma(T))\) denotes the set of all analytic functions in a neighborhood of \(\sigma(T)\). Moreover, if \(T^*\) is an algebraically \(k\)-quasiclass \(A\) operator, then \(\alpha\)-Weyl's theorem holds for \(f(T)\). Also, we prove that if \(T\) or \(T^*\) is an algebraically\(k\)-quasiclass \(A\) operator then both the Weyl spectrum and the approximate point spectrum of \(T\) obey the spectral mapping theorem for every \(f \in H(\sigma(T))\)
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