Hardy空间到加权Hardy空间上的复合算子

本文研究了从Hardy空间到加权Hardy空间上的复合算子,并给出此复合算子为有界和紧的条件。     

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.     

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.     

Dirichlet空间上Toeplitz算子的交换性(Ⅱ)

首先讨论了Ω符号的Toeplitz算子在Dirichlet空间D2上的交换性,推广了有界调和符号情形,也给出了不同于经典Hardy空间或Bergman空间上交换性的新情形;其次给山了L∞θ.1符号Toeplitz算于与径向或拟齐次符号的Toeplitz算于可交换的充要条件.所得结果与Hardy空间,Bergman空间以及Dirichlet空间D均有不同.     

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.     

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.     

广义Calderón-Zygmund算子交换子在Hardy型空间上的有界性

[b,T]表示由Lipschitz函数b与广义Calderon-Zygmund算子T生成的交换子．本文研究了[b,T]在经典Hardy空间和Herz型Hardy空间上的有界性,并且在临界点情形证明了该交换子是从Hardy空间到弱Lebesgue空间以及Herz型Hardy到弱Herz空间有界的．     

齐次群上新Hardy空间的分子特征及其应用

建立了齐次群上伴随于Herz空间和Beurling代数的Hardy空间的分子分解理论．作为其应用．研究了中心强奇异Calderon-Zygmund算子在这些空间上的有界性．     

从Hardy空间到Bloch空间的Volterra型复合算子

本文研究了从Hardy空间到Bloch型空间的Volterra型复合算子的有界性和紧性问题,事实上,我们给出了该算子的范数和本性范数刻画.同时我们研究了从Hardy空间到小Bloch型空间的Volterra型复合算子的有界性和紧性问题.     

Hardy空间上的复合算子

本文讨论n维复单位球的Hardy空间上的复合算子,主要是利用Banach代数和n维单位球上解析函数的理论,给出了这类空间上复合算子的一个特征,证明了复合算子可逆的充要条件是其符号函数属于单位球的自同构群,并且对复合算子的范数作出了估计。     

Subnormality and composition operators on the Bergman space

Following the work of C. Cowen and T. Kriete on the Hardy space, we prove that under a regularity condition, all composition operators with a subnormal adjoint on A²(D) have linear fractional symbols of the form. Moreover, we show that all composition operators on the Bergman space having these symbols have a subnormal adjoint, with larger range for the parameterr than found in the Hardy space case.     

A new class of operators and a description of adjoints of composition operators

Starting with a general formula, precise but difficult to use, for the adjoint of a composition operator on a functional Hilbert space, we compute an explicit formula on the classical Hardy Hilbert space for the adjoint of a composition operator with rational symbol. To provide a foundation for this formula, we study an extension to the definitions of composition, weighted composition, and Toeplitz operators to include symbols that are multiple-valued functions. These definitions can be made on any Banach space of analytic functions on a plane domain, but in this work, our attention is focused on the basic properties needed for the application to operators on the standard Hardy and Bergman Hilbert spaces on the unit disk.     

TWO PROBLEMS ABOUT COMPOSITION OPERATORS ON HARDY SPACE

In this paper, two problems about composition operator on Hardy space are considered. Firstly, a new estimation of the norm of a class of composition operators is given. Secondly, the cyclic behavior of the adjoint operator of a composition operator is discussed.     

A Coburn type theorem for Toeplitz operators on the Dirichlet space

A celebrated theorem of Coburn asserts that, on the setting of the Hardy space, if a Toeplitz operator is nonzero, then either it is one-to-one or its adjoint operator is one-to-one. In this paper, we show that an analogous result holds for Toeplitz operators acting on the Dirichlet space.     

Adjoints of rationally induced composition operators

We give an elementary proof of a formula recently obtained by Hammond, Moorhouse, and Robbins for the adjoint of a rationally induced composition operator on the Hardy space H² [Christopher Hammond, Jennifer Moorhouse, Marian E. Robbins, Adjoints of composition operators with rational symbol, J. Math. Anal. Appl. 341 (2008) 626-639]. We discuss some variants and implications of this formula, and use it to provide a sufficient condition for a rationally induced composition operator adjoint to be a compact perturbation of a weighted composition operator.     

Adjoints of linear fractional composition operators on the Dirichlet space

The adjoint of a linear fractional composition operator acting on the classical Dirichlet space is expressed as another linear fractional composition operator plus a two rank operator. The key point is that, in the Dirichlet space modulo constant functions, many linear fractional composition operators are similar to multiplication operators and, thus, normal. As a particular application, we can easily deduce the spectrum of each linear fractional composition operator acting on such spaces. Even the norm of each linear fractional composition operator is computed on the Dirichlet space modulo constant functions. It is also shown that all this work can be carried out in the Hardy space of the upper half plane.This work was partially supported by Plan Nacional I+D Ref. BFM2000-0360 and Junta de Andalucía Ref. FQM-260. The first named author was also supported by Plan Propio de la Universidad de Cádiz.     

局部β-凸空间L~β(μ,X)(0＜β≤1)的共轭锥的次表示定理

对于0β≤1,有限测度空间(Ω,Σ,μ)与Hilbert空间X,本文研究向量值局部β-凸函数空间L~β(μ,X)的共轭锥[L~β(μ,X)]_β~*的表示问题.在赋范锥(X_β~*,‖-‖)对μ满足Randon-Nikodym性质的条件下,证明次表示定理[L~β(μ,X)]_β~*(?)L~∞(μ,X_β~*).     

Weighted Composition Operators between Different Hardy Spaces

Let and be two analytic functions defined on such that. The operator given by is called a weighted composition operator. In this paper we deal with the boundedness, compactness, weak compactness, and complete continuity of weighted composition operators from a Hardy space H _p into another Hardy space H _q . We apply these results to study composition operators on Hardy spaces of a half-plane. Submitted: November 20, 2001.