For a compact subset K in the complex plane,let Rat(K)denote the set of the rational functions with poles off K.Given a finite positive measure with support contained in K,let R 2(K,v)denote the closure of Rat(K)in L ...For a compact subset K in the complex plane,let Rat(K)denote the set of the rational functions with poles off K.Given a finite positive measure with support contained in K,let R 2(K,v)denote the closure of Rat(K)in L 2(v)and let S v denote the operator of multiplication by the independent variable z on R 2(K,v),that is,S v f=zf for every f∈R 2(K,v).SupposeΩis a bounded open subset in the complex plane whose complement has finitely many components and suppose Rat(Ω)is dense in the Hardy space H 2(Ω).Letσdenote a harmonic measure forΩ.In this work,we characterize all subnormal operators quasi-similar to Sσ,the operators of the multiplication by z on R 2(-Ω,σ).We show that for a given v supported on-Ω,S v is quasi-similar to Sσif and only if v|?Ω?σand log(dv/dσ)∈L 1(σ).Our result extends a well-known result of Clary on the unit disk.展开更多
In this paper, let T be a bounded linear operator on a complex Hilbert H. We give and prove that every p-w-hyponormal operator has Bishop's property(β) and spectral properties; Quasi-similar p-w-hyponormal operat...In this paper, let T be a bounded linear operator on a complex Hilbert H. We give and prove that every p-w-hyponormal operator has Bishop's property(β) and spectral properties; Quasi-similar p-w-hyponormal operators have equal spectra and equal essential spectra. Finally, for p-w-hyponormal operators, we give a kind of proof of its normality by use of properties of partial isometry.展开更多
基金This work was supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,the Ministry of Education of China
文摘For a compact subset K in the complex plane,let Rat(K)denote the set of the rational functions with poles off K.Given a finite positive measure with support contained in K,let R 2(K,v)denote the closure of Rat(K)in L 2(v)and let S v denote the operator of multiplication by the independent variable z on R 2(K,v),that is,S v f=zf for every f∈R 2(K,v).SupposeΩis a bounded open subset in the complex plane whose complement has finitely many components and suppose Rat(Ω)is dense in the Hardy space H 2(Ω).Letσdenote a harmonic measure forΩ.In this work,we characterize all subnormal operators quasi-similar to Sσ,the operators of the multiplication by z on R 2(-Ω,σ).We show that for a given v supported on-Ω,S v is quasi-similar to Sσif and only if v|?Ω?σand log(dv/dσ)∈L 1(σ).Our result extends a well-known result of Clary on the unit disk.
基金Natural Science and Education Foundation of Henan Province(2007110016)
文摘In this paper, let T be a bounded linear operator on a complex Hilbert H. We give and prove that every p-w-hyponormal operator has Bishop's property(β) and spectral properties; Quasi-similar p-w-hyponormal operators have equal spectra and equal essential spectra. Finally, for p-w-hyponormal operators, we give a kind of proof of its normality by use of properties of partial isometry.
