Frink-Tukey度量化引理

一致空间的度量化问题是一致空间的基本问题之一,其主要工具是Tukey度量化引理.证明在拓扑空间的度量化问题中起主要工具之一的Frink引理与Tukey度量化引理如出一辙,可将它们称之为Frink-Tukey度量化引理.     

非紧超凸度量空间中的一个新的不动点定理及其对鞍点问题的应用

在非紧超凸度量空间中建立了一个新的不动点定理.作为应用,研究了连续选择及其不动点定理,极大元定理、Ky Fan极大极小不等式和鞍点定理.     

S~O-类函数的积分性质及其在分形中的应用

利用非标准分析的方法,给出了S~0-类实函数的一个积分不等式和一个积分等式:(1)设A是标准的完备度量空间(X,d)中的一个准标准内的子集,μ是X上的一个Borel正则有限的标准外测度.若f是X上的一个非负的S~0-类实函数,则有°(∫_Aμ)≤∫_(°A)°fdμ.特殊情况当f≡1时,有°(μ(A))≤μ(°A);(2)设E是标准的s-紧集,若f是E上的一个S~0-类实函数,则°(∫_E fdH~s)=∫_E°fdH~s,这里°(*)指的是*的影子.并给出了这些结果在分形几何中用以判断一个分形集其内部是否非空的方法及一个分形函数在Hausdorff测度空间上的积分的计算方法,并给出了相应的实例加以验证.     

Some new common fixed point results for generalized contractive multi-valued non-self-mappings

In this work, we study some new common fixed point results for generalized contractive multi-valued non-self-mappings on complete metric spaces.     

The Kripke schema in metric topology

A form of Kripke's schema turns out to be equivalent to each of the following two statements from metric topology: every open subspace of a separable metric space is separable; every open subset of a separable metric space is a countable union of open balls. Thus Kripke's schema serves as a point of reference for classifying theorems of classical mathematics within Bishop‐style constructive reverse mathematics.     

锥度量空间中锥的非正规性条件(英文)

该文首先给出锥度量空间中的锥为非正规锥的几个充要条件,随后给出一个例子进行验证.并且在锥度量空间中,当不考虑空间的完备性时,在压缩映射条件下,得到非正规锥的存在性.这些结果直接改进前人关于度量空间的一些结果,也补充他们关于锥度量空间的一些结果.     

Convergence theorems for common fixed points of asymptotically quasi-nonexpansive mappings in convex metric spaces

In this paper, we consider an implicit iteration process to approximate the common fixed points of two finite families of asymptotically quasi-nonexpansive mappings in convex metric spaces. As a consequence of our result, we obtain some related convergence theorems. Our results generalize some recent results of Khan and Ahmed [4], Khan et al. [6], Sun [12], Wittmann [14] and Xu and Ori [15].     

Criteria for the single-valued metric generalized inverses of multi-valued linear operators in banach spaces

Let X, Y be Banach spaces and M be a linear subspace in X × Y = {{x, y}|x ∈ X, y ∈ Y }. We may view M as a multi-valued linear operator from X to Y by taking M (x) = {y|{x, y} ∈ M }. In this paper, we give several criteria for a single-valued operator from Y to X to be the metric generalized inverse of the multi-valued linear operator M . The principal tool in this paper is also the generalized orthogonal decomposition theorem in Banach spaces.     

On the apollonian metric of domains in

We study the apollonian metric considered for sets in ? _n by Beardon in 1995. This metric was first introduced for plane Jordan domains by Barbilian in 1934. For a special class of plane domains Beardon showed that conformal apollonian isometries are Möbius transformations. We give here a proof of Beardon's result without conformality assumption. We show that the apollonian metric of a domain D is either conformal at every point of D, at only one point of D or at no point of D. We also present a suprising relation between convex bodies of constant width and the apollonian metric.