BMOA和VMOA空间上的紧复合算子

给出了BMOA空间上复合算子紧性的一个简单的充分必要条件.利用所给出的结果可以得到BMOA空间上紧复合算子必是Bloch空间和Hardy空间上的紧复合算子.文中也给出了VMOA空间上的类似结果.     

Volterra型算子和复合算子乘积的有界性

本文研究了从上半平面的Hardy空间到Zygmund空间上的Volterra型算子和复合算子乘积的有界性问题.利用泛函分析和复分析的方法,获得了从上半平面的Hardy空间到Zygmund空间生成的Volterra型算子和复合算子的乘积有界性刻画,推广了S.Stevic关于从上半平面的Hardy空间到Zygmund空间上的复合算子有界性的结果.     

对称Fock空间上的加权复合算子

本文研究了可分Hilbert空间上的对称Fock空间上有界(线性和反线性)加权复合算子. 完全刻画了酉加权复合算子和自伴加权复合算子, 并考虑了一类正规加权复合算子.     

从上半平面Hardy空间到增长型空间和Bloch空间上的加权复合算子的有界性

研究了从上半平面的Hardy空间到增长型空间和Bloch空间上的加权复合算子有界性的充要条件,给出了上半平面增长型空间上的加权复合算子有界性的充要条件,利用上半平面增长型空间和圆盘增长型空间之间的同构,获得了圆盘增长型空间上的加权复合算子有界性的充要条件.     

解析算子函数空间上的复合算子理论初步

本文将经典Hardy空间上复合算子的理论、方法应用到解析算子函数空间上,给出了解析算子函数空间的几个基本性质及复合算子的有界性条件.     

μ-Bergman空间到Zygmund型空间的加权复合算子

本文研究了单位圆盘D上的μBergman空间到Zygmund型空间的加权复合算子的有界性和紧性问题.利用泛函分析多复变的方法,获得了单位圆盘上μ-Bergman空间到Zygmund型空间的加权复合算子为有界算子和紧算子的充要条件.     

关于复平面上H~∞空间,β~p空间以及β_0~p空间的几个问题

本文讨论了单位圆中Hardy空间H∞到p-Bloch空间βP的复合算子T1.φ加权复合算子Tψ,(?)的有界性,也讨论了H∞到小p-Bloch空间β6的复合算子T1,(?)的有界性问题;另外还讨论了小p-Bloch空间到H∞空间的点乘子及小p-Bloch空间上复合算子的紧性等.     

多重调和函数空间的对偶空间

研究了多重调和函数空间及其上的复合算子,给出了多重调和函数空间的对偶空间,刻画了该类空间上复合算子的有界性,紧性和Fredholm性.     

第一类华罗庚域上u-Bloch空间到v-Bloch空间复合算子的有界性和紧性

本文在第一类华罗庚域上定义了一个加权Bloch空间,讨论了第一类华罗庚域上u-Bloch空间到v-Bloch空间的复合算子的有界性和紧性,分别得到了复合算子是有界算子和紧算子的充分条件和必要条件.     

Riemann曲面上的正常和拟正常复合算子

Riemann曲面M上的平方可测1-形式全体和解析1-形式全体均可构成Hilbert空间.本文讨论Riemann曲面上的解析映射导出的这类Hilbert空间上的复合算子,研究复合算子的正常性、拟正常性的诱导映射特征.特别地,当M有有限三角剖分时,证明了正常复合算子、拟正常复合算子、酉复合算子、等距复合算子和可逆复合算子等价.     

On unbounded composition operators in L^2-spaces

Fundamental properties of unbounded composition operators in \(L^2\) -spaces are studied. Characterizations of normal and quasinormal composition operators are provided. Formally normal composition operators are shown to be normal. Composition operators generating Stieltjes moment sequences are completely characterized. The unbounded counterparts of the celebrated Lambert’s characterizations of subnormality of bounded composition operators are shown to be false. Various illustrative examples are supplied.     

Invertible composition operators on Hp

The weakly closed algebras generated by certain sets of composition operators are shown to be reflexive. A structure theorem for invertible composition operators on H² is obtained and used to show that such operators are reflexive. The structure theorem shows that invertible hyperbolic composition operators are similar to cosubnormal operators built up from bilateral weighted shifts. Another consequence of the structure theorem is that the composition operators induced by hyperbolic disc automorphisms are universal. Thus the general invariant subspace problem for Hilbert space operators is contained in the problem of determining the invariant subspace lattices of these operators.     

Compact differences of composition operators

A characterization of compact difference is given for composition operators acting on the standard weighted Bergman spaces and necessary conditions are given on a larger scale of weighted Dirichlet spaces. Conditions are given under which a composition operator can be written as a finite sum of composition operators modulo the compacts. The additive structure of the space of composition operators modulo the compact operators is investigated further and a sufficient condition is given to insure that two composition operators lie in the same component.     

Hermitian Weighted Composition Operators and Bergman Extremal Functions

Weighted composition operators have been related to products of composition operators and their adjoints and to isometries of Hardy spaces. In this paper, Hermitian weighted composition operators on weighted Hardy spaces of the unit disk are studied. In particular, necessary conditions are provided for a weighted composition operator to be Hermitian on such spaces. On weighted Hardy spaces for which the kernel functions are ${(1 - \overline{w}z)^{-\kappa}}$ for κ ≥ 1, including the standard weight Bergman spaces, the Hermitian weighted composition operators are explicitly identified and their spectra and spectral decompositions are described. Some of these Hermitian operators are part of a family of closely related normal weighted composition operators. In addition, as a consequence of the properties of weighted composition operators, we compute the extremal functions for the subspaces associated with the usual atomic inner functions for these weighted Bergman spaces and we also get explicit formulas for the projections of the kernel functions on these subspaces.     

Toeplitz and composition operators on H2 (B n)

The composition operators with closed rangc on H²(B _n) are characterized, and the Fredholmness of products of Toeplitz and composition operators discussed. Moreover, using composition operators, the spectra of Toeplitz operators are studied. Project supported by the National Natural Sciencc Foundation of China and the Postdoctoral Science Foundation of China.     

COMPOSITION OPERATORS ON HARDY-ORLICZ SPACES

Properties of composition operators induced by analytic self-maps on the unit disk of the complex plane in Hardy-Orlicz spaces are discussed. Results are concerned about boundedness, invertibility, compactness, Fredholm operators and spectra of composition operators.     

不同Bers型空间之间的加权复合算子

该文讨论了单位圆盘上不同Bers型空间之间的加权复合算子的有界性、紧性和弱紧性, 给出了一些充分必要的判别条件, 特别地得到不同Bers型空间上加权复合算子的紧性与弱紧性的等价性. 这些推广了经典的复合算子与乘法算子的相关结论. 该文同时也给出了Bers型空间上复合算子的Fredholm性和闭值域问题的刻画, 完善了文献[6]中结论.     

Weighted composition operators on the Hilbert space of Dirichlet series

In this paper, we study weighted composition operators on the Hilbert space of Dirichlet series with square summable coefficients. The Hermitianness, Fredholmness and invertibility of such operators are characterized, and the spectra of compact and invertible weighted composition operators are also described.     

Which linear-fractional composition operators are essentially normal?

We characterize the essentially normal composition operators induced on the Hardy space H² by linear-fractional maps; they are either compact, normal, or (the nontrivial case) induced by parabolic nonautomorphisms. These parabolic maps induce the first known examples of nontrivially essentially normal composition operators. In addition, we characterize those linear-fractionally induced composition operators on H² that are essentially self-adjoint, and present a number of results for composition operators induced by maps that are not linear-fractional.