Compactness of composition operators on BMOA and VMOA

We give a new and simple compactness condition for composition operators on BMOA,the space of all analytic functions of the bounded mean oscillation on the unit disk.Using our results one may immediately obtain that compactness of a composition operator on BMOA implies its compactness on the Bloch space as well as on the Hardy space.Similar results on VMOA are also given.     

Wavelets associated with Hankel transform and their Weyl transforms

The Hankel transform is an important transform. In this paper, we study thewavelets associated with the Hankel transform, then define the Weyl transform of thewavelets. We give criteria of its boundedness and compactness on the L~p-spaces.     

Weak Compactness Criteria for Set Valued Integrals and Radon Nikodym Theorem for Vector Valued Multimeasures

Some criteria for weak compactness of set valued integrals are given. Also we show some applications to the study of multimeasures on Banach spaces with the Radon-Nikodym property.     

On Pseudocompact, Countably Compact, Locally Bicompact Mappings, and k-Mappings

We consider various definitions of a pseudocompact mapping and the basic properties of pseudocompact mappings. Moreover, we consider the definition of countable compactness of a continuous mapping and study the properties of a countably compact mapping similar to the corresponding properties for countably compact spaces and also the interrelation between countable compactness and pseudocompactness of mappings. We also extend the notions of local bicompactness and k-space to continuous mappings.     

Criteria for exact saturation and singular compactness

We introduce the class of unshreddable theories, which contains the simple and NIP theories, and prove that such theories have exactly saturated models in singular cardinals, satisfying certain set-theoretic hypotheses. We also give criteria for a theory to have singular compactness.     

向量优化中有效点的存在性

分别在有pre-order的无线性结构的集合和拓扑空间中，给出了有效点的存在性。作为应用，讨论了向量优化问题中解的存在性。最后给出了紧、弱紧、锥紧、锥半紧、上序紧、下序紧、上序半紧、准上序半紧和准下序半紧等之间的关系。     

具Hardy-Sobolev临界指数的奇异椭圆方程多解的存在性

运用变分方法研究了下面问题-Δpu=μupx(s)s-2u f(x,u),x∈Ω,u=0,x∈Ω,多重解的存在性,其中Ω是一个具有光滑边界的有界区域.     

Boundedness and compactness of Volterra type integral operators

We introduce some nested classes of Volterra type integral operators. For the operators of these classes we establish criteria for boundedness and compactness in Lebesgue spaces.     

Some topological properties in optimization theory

We study some topological properties of the vector sum of two sets, and we introduce the concept of strong cone compactness, a slightly strengthened version of the notion of cone compactness, which is used frequently in vector optimization. Furthermore, we establish a generalization of the well-known fact that the continuous image of a compact set is compact.     

Convergence and Compactness Properties for a Family of 2-D Discontinuous Signals

In this paper, convergence and compactness properties for sets of possibly discontinuous functions on ² are discussed. The issue appears to be relevant with respect to optimization and identification problems for 2-D images.Several convergence properties are provided and compared for a class of discontinuous 2-D functions with sufficiently regular discontinuity sets.Two sufficient compactness criteria are given; the first one extends to the 2-D case previously known results on the 1-D Skorohod topology.     

Orlicz序列空间的对偶映射

本文研究Orlicz序列空间的对偶映射,给出对偶映象集为弱紧集的充分必要 条件.作为推论,得到Orlicz序列空间的弱接近光滑性的充要条件.     

On dynamic programming: Compactness of the space of policies

The compactness of the set of policies in a dynamic programming decision model, which guarantees the existence of an optimal policy, is proven by reducing the problem to the compactness of the set of probability measures which are induced by the policies. When studying the set of probability measures, use is made of the weak topology and the so-called ws^∞-topology. A definition and a discussion of the latter topology is given in this paper, where we pay attention to criteria for relative compactness.     

单位球面中极小子流形的C∞紧性

本文研究了单位球面中极小子流形的C∞紧性,并得到两个紧性定理.作为应用,我们证明了存在正数δ(n),如果单位球面中极小子流形的第2基本形式的长度平方小于;2/3+δ(n),则它必须是全测地的或微分同胚于Veronese曲面.     

Inversion Formula for the Dunkl-Wigner Transform and Compactness Property for the Dunkl-Weyl Transforms

We define and study the Fourier-Wigner transform associated with the Dunkl operators,and we prove for this transform an inversion formula.Next,we introduce and study the Weyl transforms W_σ associated with the Dunkl operators,where cr is a symbol in the Schwartz space S(R~d×R~d).An integral relation between the precedent Weyl and Wigner transforms is given.At last,we give criteria in terms of σ for boundedness and compactness of the transform W_σ.     

Ascoli-Arzela定理的一个推广及应用

给出了无穷区间上一类抽象连续函数族相对紧性判断的一个充分必要条件，并应用它获得了抽象空间上一阶微分方程的终值问题和Ｆｒｅｄｈｏｌｍ型积分方程解的存在性。     

一些算子的交换子在广义Morrey空间上的紧性

本文主要研究分数次积分算子、Marcinkiewicz积分、带光滑核的pseudo-differential算子的交换子在广义Morrey空间M_p，ω（Rⁿ）上的紧性.注意它们的处理方法分别不同.     

一类拟线性椭圆方程组非平凡解的存在性

首先证明了一个抽象的紧性定理,然后借此定理证明了对应于一类拟线性椭圆方程组的泛函在比Boccardo和De．Figueiredo(2002)的条件更弱的条件(文中记为弱类(AR)条件)下满足(C)条件,并利用山路引理证明了这类拟线性椭圆方程组非平凡解的存在性,最后举出两个例子验证了文中所给条件(即弱类(AR)条件)的确比Boccardo和De．Figueiredo(2002)的条件弱．     

Best approximation properties in spaces of measurable functions

We research proximinality of μ‐sequentially compact sets and μ‐compact sets in measurable function spaces. Next we show a correspondence between the Kadec–Klee property for convergence in measure and μ‐compactness of the sets in Banach function spaces. Also the property S is investigated in Fréchet spaces and employed to provide the Kadec–Klee property for local convergence in measure. We discuss complete criteria for continuity of metric projection in Fréchet spaces with respect to the Hausdorff distance. Finally, we present the necessary and sufficient condition for continuous metric selection onto a one‐dimensional subspace in sequence Lorentz spaces .     

关于二维球面上的Ricci流的一个注记

给出Hamilton和Chow关于二维球面上的Ricci流的一个定理的新证明．这个证明结合了Hamilton关于Ricci流的紧性定理和二维ancientp解的分类和Perelman的非塌缩定理．     

Pullback attractors for non-autonomous reaction-diffusion equations on ?n

We study the long time behavior of solutions of the non-autonomous reaction-diffusion equation defined on the entire space Rn when external terms are unbounded in a phase space. The existence of a pullback global attractor for the equation is established in L2(Rn) and H1(Rn), respectively. The pullback asymptotic compactness of solutions is proved by using uniform a priori estimates on the tails of solutions outside bounded domains.