自反Banach空间算子闭值域的若干性质

本文讨论自反Banach空间算子T－正则点,证明了T及其共轭算子T^*在闭值域区域上的T－正则点集的关系,ρb（T）与ρb(T)的若干结构表示。     

算子矩阵值域的闭性及其应用

令{H}和{K}均为无限复可分的Hilbert空间. 定义M_X=(A&C\\X&B\)为作用在{H}}\oplus{K}上的2x2算子矩阵, 其中X为从{H}到{K}上未知的有界线性算子.在本文中, 基于R(C)的闭性对某个(或任意的)X\in{B}}({H,K}}), 使得R(M_{X})为闭集的充要条件做了等价刻画.另外, 研究了算子矩阵M_{X的半Fredholm性与广义Weyl性并给出了一些相应的结论.     

微分算子扰动问题的值域研究

本文研究作用在C2周期函数空间上的微分算子u→u″ g(u) ,其中g(u)为连续有界函数.我们将证明上述微分算子的值域限制在周期函数空间的“超曲面”中.     

一类无界算子的二次数值域和谱

该文研究了从二阶偏微分方程z(t)-Bz(t)+Az(t)=0中抽象出的无界算子M=[■]的谱分布,其中A为一致正自伴算子,B为增生算子.先分析了算子M的闭性、逆有界等基本性质,并证明了分块算子矩阵M|_H1×H1的闭包与算子M相等,其中H₁=D(A)为赋有范数‖x‖H₁=‖Ax‖的Hilbert空间,然后利用分块算子矩阵M|_H1×H1的二次数值域估计了算子M的谱的范围.     

多变量Toeplitz算子的联合谱与联合数值域

一般地,我们用B~n表示C~n中单位球,S~n表示B~n的边界;对0相似文献   

无穷维Hamilton算子的二次数值域

研究了一类无界无穷维Hamilton算子的二次数值域的性质,进而,应用二次数值域来刻画了无穷维Hamilton算子谱的分布范围,并给出了二次数值域的闭包包含谱集的结论.     

伪单调算子紧扰动的值域

设X是自反Banach空间且X和X^*均为局部一致凸空间,D是X的开、有界、凸子集,T：D→X^*是伪单调算子（pseudo-monotone),C:D→X^*是紧算子或全连续算子。利用（S ）型算子的度理论,我们建立了T C值域性质的几个结果,这些结果对研究各类方程问题有所应用。     

关于初等算子∑(X):AX+XB+CDX的值域

设A，B和C是Hilbert空间H上的紧算子，定义B（H）上的初等算子，∑(X)=AX XB CXD。本文我们给出∑值域闭的一些充分或必要条件。     

A solution to a problem on invertible disjointness preserving operators

We construct an invertible disjointness preserving operator on a normed lattice such that is not disjointness preserving.

     

Polar decomposition of order bounded disjointness preserving operators

We constructively prove (i.e., in ZF set theory) a decomposition theorem for certain order bounded disjointness preserving operators between any two Riesz spaces, real or complex, in terms of the absolute value of another order bounded disjointness preserving operator. In this way, we constructively generalize results by Abramovich, Arensen and Kitover (1992), Grobler and Huijsmans (1997), Hart (1985), Kutateladze, and Meyer-Nieberg (1991).

     

Stability of disjointness preserving mappings

Let and be compact Hausdorff spaces and let . A linear mapping is called -disjointness preserving if implies that . If is a continuous or surjective -disjointness preserving linear mapping, we prove that there exists a disjointness preserving linear mapping satisfying . We also prove that every unbounded -disjointness preserving linear functional on is disjointness preserving.

     

Characterizations of Disjointness preserving operators on vector-valued function spaces

We characterize compact and completely continuous disjointness preserving linear operators on vector-valued continuous functions as follows: a disjointness preserving operator is compact (resp. completely continuous) if and only if

for all

where is continuous and vanishes at infinity in the uniform (resp. strong) operator topology, and is compact (resp.  is uniformly completely continuous).

     

The structure of compact disjointness preserving operators on continuous functions

Let T be a compact disjointness preserving linear operator from C₀(X) into C₀(Y), where X and Y are locally compact Hausdorff spaces. We show that T can be represented as a norm convergent countable sum of disjoint rank one operators. More precisely, T = Σ_n δ ?h_n for a (possibly finite) sequence {x_n }_n of distinct points in X and a norm null sequence {h_n }_n of mutually disjoint functions in C₀(Y). Moreover, we develop a graph theoretic method to describe the spectrum of such an operator (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Maximal ideals of disjointness preserving operators

Let L and M be vector lattices with M Dedekind complete, and let Lr(L,M) be the vector lattice of all regular operators from L into M. We introduce the notion of maximal order ideals of disjointness preserving operators in Lr(L,M) (briefly, maximal δ-ideals of Lr(L,M)) as a generalization of the classical concept of orthomorphisms and we investigate some aspects of this ‘new’ structure. In this regard, various standard facts on orthomorphisms are extended to maximal δ-ideals. For instance, surprisingly enough, we prove that any maximal δ-ideal of Lr(L,M) is a vector lattice copy of M, when L, in addition, has an order unit. Moreover, we pay a special attention to maximal δ-ideals on continuous function spaces. As an application, we furnish a characterization of lattice bimorphisms on such spaces in terms of weigthed composition operators.     

Some remarks on disjointness preserving operators

In this note we present a simple proof of the following results: if T: E E is a lattice homomorphism on a Banach lattice E, then: i) (T)={1} implies T=I; and ii) r(T–I)<1 implies TZ(E), the center of E.     

Normality preserving multiplication operators

We show that a multiplication operator (T)=ATB is normality preserving if and only if it is hyponormality preserving, if and only if it is either of the formA=fg,B=h f, orA=D,B=D* for someC andD* D=I. Also we show that is (semi-) Fredholmness prserving if and only ifA andB are (semi-) Fredholm operators.Supported by the Science Foundation of Zhejiang Province and NSF.     

Completely bounded disjointness preserving operators between Fourier algebras

In this paper, we characterize surjective completely bounded disjointness preserving linear operators on Fourier algebras of locally compact amenable groups. We show that such operators are given by weighted homomorphisms induced by piecewise affine proper maps.     

Characterization of the duals of lattices of continuous functions with respect to disjointness preserving groups

The duals of and with respect to disjointness preserving groups are characterized. A. Plessner's result (1929) about the translation group is extended. A Wiener-Young type theorem for disjointness preserving groups is obtained.