Banach空间上闭算子的可约性

本文从谱约化的角度讨论Banach空间上的闭可约化算子,闭谱算子及闭可分解算子的谱特征,并研究了这三类算子间的关系,最后给出Banach空间上一个闭线性算子成为闭谱算子的充分必要条件。设C表示复平面,C_∞表示扩充复平面,即C_∞=C∪{0},X表示复Banach空间,T表示X上的闭线性算于,D(T)表示T的定义域,σ(T),ρ(T)分别表示T的谱     

L~p(X,A,μ)上的紧复合算子

设(X,,μ)是σ-有限测度空间,φ:X→X是非奇异可测变换,则如下定义的映照: C_φf(x)=f[φ(x)]是L~p(X,,μ)上的线性算子。如果C_φ是有界的,则称C_φ为L~p(X,,μ)上的可测变换φ导出的复合算子。我们已知:C_φ为有界复合算子的充要条件是存在M>0,使得对任何     

线性有界算子的稳定点谱

本文研究了可分复 Hilbert 空间上线性有界算子 T 的稳定点谱σ_(ps)(T)和紧稳定点谱σ_(pks)(T)的拓扑结构及其摄动问题.     

算子概率范数与共鸣定理

提出概率赋范线性空间上集合有界性的简化定义,利用算子概率范数概念。进一步研究概率赋范线性空间上的线性算子理论,并在算子概率赋范空间上,建立了概率有界、概率半有界、非概率无界意义下的共鸣定理。     

Zygmund空间上的微分复合算子

讨论Zygmund空间E={f∈H(D):sup_(z∈D)(l-|z|~2)|f″(z)|∞}上的微分复合算子DC_φ,这里C_φ是复合算子,D是微分算子.得到了DC_φ在Zygmund空间E和小Zygmund空间E_0上是有界算子与紧算子的充分必要条件.     

超球上Bloch型空间之间复合算子再刻画

对所有的0＜p,q＜∞,本文得到了C~n中超球上Bloch型空间β~p与β~q之间的复合算子C_为有界算子和紧算子的充要条件,同时获得了几个推论．     

拟紧算子的谱性质和遍历性

对Banach空间X上的一个线性有界算子A,若存在一紧算子Q和一自然数m,使得‖A~m-Q‖<1,则称A是拟紧算子.本文使用算子谱理论的方法,从多个方面刻划了算子的拟紧性.     

自反算子代数的环自同构

设A是Banach空间X上的自反算子代数,并且A的不变子空间格Lat A满足0+≠0和X_≠X,αA→A是环自同构.如果X是实空间,并且dim X±＞1,则存在X上的线性有界可逆算子A,使得α(T)=ATA-1,T∈A;如果X是复空间,并且dim X±=∞,则α(T)=ATA-1,T∈A.其中AX→X是线性、或者共轭线性有界可逆算子.     

关于非正常算子(Ⅱ)

<正> 设A是希尔伯特空间H中的线性有界算子,把A写成u+iv,其中u和v都是有界的自共轭算子.在[1]中作者称Q=i(vu-uv)为A的导算子,又考察了当QH是一维的而且H是包含QH并约化u的最小线性闭子空间时,算子A的奇异积分模型(可参看[2],[3]).本文中,把前文结果推广到Q≥0的情况(Q≤0时完全类似),得到这种算子(称为半正常算子)的模型     

有界上三角算子矩阵的亏谱

讨论了希尔伯特空间上有界上三角算子矩阵的亏谱扰动性质,当对角元算子给定时,得到上三角算子矩阵的亏谱恰等于对角元算子的亏谱之并集的充要条件,特别地,给出有界上三角Hamilton型算子矩阵相应问题成立的条件,并辅以实例佐证.     

A complete characterization of exponential stability for discrete dynamics

For a discrete dynamics defined by a sequence of bounded and not necessarily invertible linear operators, we give a complete characterization of exponential stability in terms of invertibility of a certain operator acting on suitable Banach sequence spaces. We connect the invertibility of this operator to the existence of a particular type of admissible exponents. For the bounded orbits, exponential stability results from a spectral property. Some adequate examples are presented to emphasize some significant qualitative differences between uniform and nonuniform behaviour.     

单位球上不同Hardy空间之间的复合算子

研究了C~N中单位球B上,当q相似文献   

Norms and spectral radii of linear fractional composition operators on the ball

We give a new proof that every linear fractional map of the unit ball induces a bounded composition operator on the standard scale of Hilbert function spaces on the ball, and obtain new norm bounds analogous to the standard one-variable estimates. We also show that Cowen's one-variable spectral radius formula extends to these operators. The key observation underlying these results is that every linear fractional map of the ball belongs to the Schur-Agler class.     

商不可分解Banach空间上线性算子的谱

This paper discusses the special properties of the spectrum of linear operators (in particular, bounded linear operators) on quotient indecomposable Banach spaces; shows that in such spaces generators of Co-groups are always bounded linear operators, and that generators of Co-semigroups satisfy the spectral mapping theorem; and gives an example to show that the generators of Co-semigroups in quotient indecomposable spaces are not necessarily bounded.     

Compact adjoint operators and approximation properties

This paper is concerned with the space of all compact adjoint operators from dual spaces of Banach spaces into dual spaces of Banach spaces and approximation properties. For some topology on the space of all bounded linear operators from separable dual spaces of Banach spaces into dual spaces of Banach spaces, it is shown that if a bounded linear operator is approximated by a net of compact adjoint operators, then the operator can be approximated by a sequence of compact adjoint operators whose operator norms are less than or equal to the operator norm of the operator. Also we obtain applications of the theory and, in particular, apply the theory to approximation properties.     

谱表示

<正> Stone M.对Hilbert空间中一个具有简单谱的自伴算子建立了谱表示定理,即有实轴上的有限Borel测度μ,使得同构于L~2(μ),同时变A为乘以自变量λ的算子.Jauch等([2])讨论了一列交换的自伴算子完全集谱表示定理,但要求一个关于测度绝对连续性的假定.此外,依据约化理论([3])可知,如果A是可分Hilbert空间的自伴     

p-ω-亚正规算子的一些性质

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.     

Linear Combinations of Composition Operators on the Fock-Sobolev Spaces

We study linear combinations of composition operators acting on the Fock-Sobolev spaces of several variables. We show that such an operator is bounded only when all the composition operators in the combination are bounded individually. In other words, composition operators on the Fock-Sobolev spaces do not possess the same cancelation properties as composition operators on other well-known function spaces over the unit disk. We also show the analogues for compactness and the membership in the Schatten classes. In particular, compactness and the membership in some/all of the Schatten classes turn out to be the same.     

Closed Semistable Operators and Singular Differential Equations

We study a class of closed linear operators on a Banach space whose nonzero spectrum lies in the open left half plane, and for which 0 is at most a simple pole of the operator resolvent. Our spectral theory based methods enable us to give a simple proof of the characterization of C ₀-semigroups of bounded linear operators with asynchronous exponential growth, and recover results of Thieme, Webb and van Neerven. The results are applied to the study of the asymptotic behavior of the solutions to a singularly perturbed differential equation in a Banach space.     

Closed range positive operators on Banach spaces

A bounded positive operator on a Hilbert space has closed range if and only if the operator and its square root have common ranges. We give an extension of this result for positive operators acting on reflexive Banach spaces. Some other results concerning positive operators on Hilbert spaces are carried over to this general case.