The Quasiapproximate (ζ+ζ)-invariants of Essentially Normal Operators

摘要

let ξ be a complex separable Hilbert space, ξ(ξ) the set of bounded linear operators on ξ and ξ(ξ) the ideal of compact operators on ξ. Given T∈ξ(ξ), σ(T) and σ_e(T) denote the spectrum and the essential spectrum of T, respectively. For Δ, a clopen subset of σ(T), E(Δ;T) denotes the corresponding Riesz idempotent And ξ(Δ;T):=ran E(Δ;T).