Downward Sets and their separation and approximation properties

We develop a theory of downward subsets of the space ^I, where I is a finite index set. Downward sets arise as the set of all solutions of a system of inequalities x^I,f_t(x)0 (tT), where T is an arbitrary index set and each f _t (tT) is an increasing function defined on ^I. These sets play an important role in some parts of mathematical economics and game theory. We examine some functions related to a downward set (the distance to this set and the plus-Minkowski gauge of this set, which we introduce here) and study lattices of closed downward sets and of corresponding distance functions. We discuss two kinds of duality for downward sets, based on multiplicative and additive min-type functions, respectively, and corresponding separation properties, and we give some characterizations of best approximations by downward sets. Some links between the multiplicative and additive cases are established.     

Characterizations of Maximal Elements for Extended Real Valued Increasing and Co-Radiant Functions

In this article, we first investigate maximal elements of the support set for non-positive valued (strictly) increasing and co-radiant functions. We then characterize maximal elements of the support set for extended real valued (strictly) increasing and co-radiant functions. Finally, we present conditions which distinguish maximal elements of the support set for this class of functions.     

Banach空间上凸集的凸性

以Banach空间的一般凸集为研究对象,将Banach空间的凸性研究推广到了内部非空的凸集上．打破了从单位球出发研究Banach空间几何的具有局限性的研究方法,给出了严格凸集的若干特征刻画及性质,并得到了严格凸集和光滑集之间的对偶定理．     

Global optimization of the difference of affine increasing and positively homogeneous functions

The theory of increasing and positively homogeneous (IPH) functions defined on a real topological vector space X has well been developed. In this paper, we first give various characterizations for maximal elements of the support set of this class of functions. As an application, we present various characterizations for maximal elements of the support set of affine IPH functions. Finally, we investigate necessary and sufficient conditions for the global minimum of the difference of two strictly affine IPH functions.     

一类物元可拓集的性质研究

提出了物元等价类概念,并利用子集合X和属性子集R对物元集合S(U,A,V,f)在集合论域U上构造了一类可拓集合A~,并讨论了A~关于X和R的一些相关性质.     

关于不变集的一个注记

§ 1.Ｉｎｔｒｏｄｕｃｔｉｏｎ　ＬｅｔＲｎｂｅｎｄｉｍｅｎｓｉｏｎａｌＥｕｃｌｉｄｅａｎｓｐａｃｅ,ａｎｄ (ｆ1,… ,ｆｍ,Ｒｎ)ａｃｏｎｔｒａｃｔｉｏｎｉｔｅｒａｔｅｄｆｕｎｃｔｉｏｎｓｙｓｔｅｍ .Ｉｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｔｈｅｒｅｅｘｉｓｔｓａｕｎｉｑｕｅｎｏｎ ｅｍｐｔｙｃｏｍｐａｃｔｓｅｔＥｓｕｃｈｔｈａｔＥ =∪ｍｉ=1 ｆｉ(Ｅ) .ＷｅｃａｌｌｔｈｅｓｅｔＥｉｎｖａｒｉｎｔｓｅｔｆｏｒ (ｆ1,… ,ｆｍ,Ｒｎ) .　Ｌｅｔ (ｆ1,… ,ｆｍ,Ｒｎ)ｂｅａｃｏｎｔｒａｃｔｉｏｎｉｔｅｒａｔｅｄｆｕｎｃｔ…     

Weakly Convex Sets and Their Properties

In this paper, the notion of a weakly convex set is introduced. Sharp estimates for the weak convexity constants of the sum and difference of such sets are given. It is proved that, in Hilbert space, the smoothness of a set is equivalent to the weak convexity of the set and its complement. Here, by definition, the smoothness of a set means that the field of unit outward normal vectors is defined on the boundary of the set; this vector field satisfies the Lipschitz condition. We obtain the minimax theorem for a class of problems with smooth Lebesgue sets of the goal function and strongly convex constraints. As an application of the results obtained, we prove the alternative theorem for program strategies in a linear differential quality game.     

亚纯函数的例外集

自从Ｌｅｈｔｏ Ｏ．［１］提出例外集的概念后,这方面已有不少工作,但这些工作基本上是局限于整函数来做的,主要原因是极点给证明带来很大困难．本文证明了任一个满足δ（∞,ｆ）＞３／４的超越亚纯函数ｆ（ｚ）,ｆｋＱ［ｆ］在任一不含ｆ和Ｑ［ｆ］极点的可数个圆盘并集之外取任何非零复数无穷次,其中ｋ≥１５／８＋１／２ГＱ,ГＱ是ｆ的微分多项式 Ｑ［ｆ］的权．本文的结果推广了 Ｈａｘｍａｎ等人的结论．     

广义凸函数相关集合的稠密性问题

应用新方法,研究十二类广义凸函数相关集合的稠密性问题.证明了其中的八个集合在[0,1]中是稠密的.应用反例说明了其中的四个集合在[0,1]中不必稠密.     

近似凸集的某些性质

主要研究了两类近似凸集的关系和性质.首先,举例说明两类近似凸集没有相互包含关系.其次,在近似凸集(nearly convex)条件下,证明了在一定条件下函数上图是近似凸集与凸集的等价关系.同时,考虑了近似凸函数与函数上图是近似凸集的等价刻画、近似凸函数与函数水平集是近似凸集的必要性,并用例子说明近似凸函数与函数水平集是...     

单调集对策及合成对策的边缘值

本文给出了单调集对策及其合成对策的边缘值，它类似于我们所熟知的TU—对策的Shapley值及文献[6]．集对策的边缘值的意义在于允许局中人共享项目．这使得不能分割的项目在局中人之间的分配成为可能．我们给出了这种边缘值的一些性质，并讨论了合成集对策的核及其子对策的核之间的关系．     

Voronoi Diagrams of Real Algebraic Sets

A collection of n (possibly singular) semi-algebraic sets in ^d of dimension d–1, each defined by polynomials of maximal degree , has ((n) ^d ) first-order Voronoi cells (for any fixed d). In the nonhypersurface case, where the maximal dimension of the semi-algebraic sets is m d–2, the number of first-order Voronoi cells is bounded above by O(n ^{m+1 d} ) (for nonsingular semi-algebraic sets) or by O((n) ^d ) (in general). The complexity of the entire kth-order Voronoi diagram of a generic collection of n non-singular real algebraic sets in R ^d of maximal dimension m<d and maximal degree is O(n ^{min(d+k,2d)2(m+1)d} ).     

A further characteristic of abstract convexity structures on topological spaces

In this paper, we give a characteristic of abstract convexity structures on topological spaces with selection property. We show that if a convexity structure C defined on a topological space has the weak selection property then C satisfies H₀-condition. Moreover, in a compact convex subset of a topological space with convexity structure, the weak selection property implies the fixed point property.     

Increasing Convex-Along-Rays Functions with Applications to Global Optimization

Increasing convex-along-rays functions are defined within an abstract convexity framework. The basic properties of these functions including support sets and subdifferentials are outlined. Applications are provided to unconstrained global optimization using the concept of excess function.     

Abstract convexity of extended real-valued ICR functions

The theory of non-negative increasing and co-radiant (ICR) functions defined on ordered topological vector spaces has been well developed. In this article, we present the theory of extended real-valued ICR functions defined on an ordered topological vector space X. We first give a characterization for non-positive ICR functions and examine abstract convexity of this class of functions. We also investigate polar function and subdifferential of these functions. Finally, we characterize abstract convexity, support set and subdifferential of extended real-valued ICR functions.     

On a Class of Recursively Enumerable Sets

We define a class of so-called ∑(n)-sets as a natural closure of recursively enumerable sets W_n under the relation “∈” and study its properties.