Article ID Journal Published Year Pages File Type
9502696 Journal of Mathematical Analysis and Applications 2005 12 Pages PDF
Abstract
A Hilbert space operator T∈B(H) is hereditarily normaloid (notation: T∈HN) if every part of T is normaloid. An operator T∈HN is totally hereditarily normaloid (notation: T∈THN) if every invertible part of T is normaloid. We prove that THN-operators with Bishop's property (β), also THN-contractions with a compact defect operator such that T−1(0)⊆T∗−1(0) and non-zero isolated eigenvalues of T are normal, are not supercyclic. Take A and B in THN and let dAB denote either of the elementary operators in B(B(H)): ΔAB and δAB, where ΔAB(X)=AXB−X and δAB(X)=AX−XB. We prove that if non-zero isolated eigenvalues of A and B are normal and B−1(0)⊆B∗−1(0), then dAB is an isoloid operator such that the quasi-nilpotent part H0(dAB−λ) of dAB−λ equals (dAB−λ)−1(0) for every complex number λ which is isolated in σ(dAB). If, additionally, dAB has the single-valued extension property at all points not in the Weyl spectrum of dAB, then dAB, and the conjugate operator dAB∗, satisfy Weyl's theorem.
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Physical Sciences and Engineering Mathematics Analysis
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