紧空间上的正则向量值测度

J.Diestel和J.J.Uhl,Jr在他们的专著《Vector Measures》一书的第六章讨论了向量测度与C(Ω)上有界线性算子的关系。我们利用其中的一些结果得到紧空间上一类正则向量测度通过数值测度表示的定理。设Ω是紧Hausdorff空间,∑是Ω的所有Borel集构成的σ-代数,X是Banach空间,G:∑→X称为Ω上的正则X-值测度,若(i)当     

非紧距离空间上的Lipschitz-α算子空间

引入了由非紧距离空间(D,d)到一般Banach空间Y中的Lipschitz-α算子以及相应的算子空间Lα(D,Y)和lα(D,Y),证明了Lipschitz-α算子空间Lα(D,Y)与lα(D,Y)∩Lα(D,Y)关于范数‖T‖α,e=‖Te‖ Lα(T)是Banach空间,并讨论了(lαB(D,Y),‖·‖α,e)、(LαB(D,Y),‖·‖α,e)及(Lα(D,Y),‖·‖α,e)之间的关系.     

次可加测度压的一个注记

利用非紧集上拓扑压的定义,对任意一个不变测度和一族紧度量空间上的次可加势函数,引进了一个新的次可加测度压的定义.在某些假设下,对任意一个遍历测度,证明了新定义的次可加测度压等于用生成集定义的次可加测度压.进一步得到了一个逆变分原理,即次可加测度压等于在某个非紧集上的拓扑压.     

Morrey型空间刻画和Carleson测度

定义了解析Morrey型空间H_K~p,并利用H~p空间范数给出了其刻画.还运用Carleson测度刻画了从H_K~p到帐篷型空间J_K~p(μ)嵌入映射的有界性及紧性,其中,权函数K:[0,∞)→[0,∞)是一个右连续且非递减的函数.     

s-齐性空间与s-齐性测度

Bylund和Gudayol(2000)指出,若紧度量空间X有有限的Assouad维数s和正的下Assouad维数t,则对任意s′s和0t′t,度量空间X上存在一个概率测度μ是上s′-齐性和下t′-齐性的.他们在构造测度的过程中需要无限次的调整.本文用与WU(1998)对偶的方法给出一种比较简单和直观的证明.     

一类半线性微分方程温和解的精确可控性

本文利用非紧测度研究了Banach空间中非局部项满足Lipschitz连续条件下半线性微分方程温和解的精确可控性.在研究过程中没有使用以往文献中关于非紧测度假设的正则性条件,而是利用不同拓扑空间中非紧测度的估计,并利用商空间的性质给出了合适的控制函数,得到了微分方程温和解的精确可控性.因此,我们的研究结果可以认为是可控性领域结论的推广.     

动力系统中紧的指数吸引集的存在性

本文研究了一般形式的无穷维动力系统.利用非紧性测度理论,当非紧性测度指数衰减时,获得了紧的指数吸引集的存在性条件.同时给出了易于验证非紧性测度指数衰减的方法.     

超空间中紧集的凸包

经典的Mazur定理叙述的是,若K是Banach空间X的紧子集,则K的闭凸包,conv(K)也是紧的．设(CC(X),h)是X的所有非空紧凸子集族,并赋予其Hausdorff距离h．假设K是CC(X)的紧子集,将在超空间CC(X)上定义凸性,并证明(conv(K),h)是紧的.     

关于广义导算子的左右本性逆

在本文中,X、Y等表示Banach空间,H、K等表示Hilbert空间,如无特别注明均为无限维的。[X,Y]表示由X到Y的有界线性算子空间,当Y=X时记作B(X)。K(X)表示X上的紧算子全体所成之集。 设A_i∈B(X)、B_i∈B(Y)(i=1,2,…,n),由     

几类非紧性测度之间的比较性质

首先列举了几类不同意义下的非紧性测度,并对这几种非紧性测度作了比较,得到了两个重要的比较性质.     

Measures of Non-compactness of Operators on Banach Lattices

[Indag. Math.(N.S.) 2(2) (1991), 149–158; Uspehi Mat. Nauk 27(1(163)) (1972), 81–146] used representation spaces to study measures of non-compactness and spectral radii of operators on Banach lattices. In this paper, we develop representation spaces based on the nonstandard hull construction (which is equivalent to the ultrapower construction). As a particular application, we present a simple proof and some extensions of the main result of [J. Funct. Anal. 78(1) (1988), 31–55] on the monotonicity of the measure of non-compactness and the spectral radius of AM-compact operators. We also use the representation spaces to characterize d-convergence and discuss the relationship between d-convergence and the measures of non-compactness.     

ASYMPTOTICALLY ISOMETRIC COPIES OF lp (1≤p＜∞) AND c0 IN BANACH SPACES

Let X be a Banach space. If there exists a quotient space of X which is asymptotically isometric to l1, then X contains complemented asymptotically isometric copies of l1. Every infinite dimensional closed subspace of l1 contains a complemented subspace of l1 which is asymptotically isometric to l1. Let X be a separable Banach space such that X* contains asymptotically isometric copies of lp (1 ＜ p ＜∞). Then there exists a quotient space of X which is asymptotically isometric to lq (1/p 1/q=1). Complementedasymptotically isometric copies of c0 in K(X, Y) and W(X, Y) are discussed. Let X be a Gelfand-Phillips space. If X contains asymptotically isometric copies of c0, it has to contain complemented asymptotically isometric copies of c0.     

Asymptotically Isometric Copy of lβ (0 ＜β ＜ 1) in Spaces of Bounded Linear Operators

Assume X is a normed space, every x* ∈ S(X*) can reach its norm at some point in B(X), and Y is a β-normed space. If there is a quotient space of Y which is asymptotically isometric to lβ, then L(X, Y) contains an asymptotically isometric copy of lβ. Some sufficient conditions are given under which L(X, Y) fails to have the fixed point property for nonexpansive mappings on closed bounded β-convex subsets of L(X, Y).     

关于熵数、非紧性的测量和插值的一些注记(英文)

本文综述了关于熵数和非紧性的测量的插值性质,本文也描述了经典结果及几个非常新的结果。     

Dentability indices with respect to measures of non-compactness

We study the relationships between the ordinal indices of set derivations associated to several measures of non-compactness. We obtain applications to the Szlenk index, improving a result of Lancien, and LUR renorming, providing a non-probabilistic proof of a result of Troyanski.     

On a Measure of Non-compactness for Some Classical Operators

The measure of non-compactness is estimated from below for various operators, including the Hardy-Littlewood maximal operator, the fractional maximal operator and the Hilbert transform, all acting between weighted Lebesgue spaces. The identity operator acting between weighted Lebesgue spaces and also between the counterparts of these spaces with variable exponents is similarly analysed. These results enable the lack of compactness of such operators to be quantified.     

包含$l^{\beta}(0<\beta<1)$渐近等距翻版的有界线性算子空间

Assume X is a normed space,every x ＊ ∈ S（X＊） can reach its norm at some point in B（X）,and Y is a β-normed space.If there is a quotient space of Y which is asymptotically isometric to l β,then L（X,Y） contains an asymptotically isometric copy of l β.Some sufficient conditions are given under which L（X,Y） fails to have the fixed point property for nonexpansive mappings on closed bounded β-convex subsets of L（X,Y）.     

Smooth automorphisms and path-connectedness in Borel dynamics

Let Aut(X, B) be the group of all Borel automorphisms of a standard Borel space (X, B). We study topological properties of Aut(X, B) with respect to the uniform and weak topologies, τ and p, defined in [Bezuglyi S., Dooley A.H., Kwiatkowski J., Topologies on the group of Borel automorphisms of a standard Borel space, Preprint 2003]. It is proved that the class of smooth automorphisms is dense in (Aut(X, B), p). Let Ctbl(X) denote the group of Borel automorphisms with countable support. It is shown that the topological group Aut₀(X, B) = Aut(X, B)/Ctbl(X) is path-connected with respect to the quotient topology τ₀. It is also proved that Aut₀(X, B) has the Rokhlin property in the quotient topology p₀, i.e., the action of Aut₀(X,B) on itself by conjugation is topologically transitive.     

强向量拟均衡问题解的存在性(英文)

设X是一个实的Hausdorff拓扑向量空间,Y是一个实的局部凸向量空间,C是Y中的闭凸锥,K（?）X是一个紧子集.F:X×X→Y是一个双向量函数,G:K→2K是一个集合值映射.我们考虑下面的强拟均衡问题:存在x∈G（x）,使得对任意的y∈G（x）,成立F（x,y）∈C.本文证明了当F是半连续时,上述问题解的存在性结论.     

Mahler measures in a cubic field

We prove that every cyclic cubic extension E of the field of rational numbers contains algebraic numbers which are Mahler measures but not the Mahler measures of algebraic numbers lying in E. This extends the result of Schinzel who proved the same statement for every real quadratic field E. A corresponding conjecture is made for an arbitrary non-totally complex field E and some numerical examples are given. We also show that every natural power of a Mahler measure is a Mahler measure.