On farthest points of sets

For a convex closed bounded set in a Banach space, we study the existence and uniqueness problem for a point of this set that is the farthest point from a given point in space. In terms of the existence and uniqueness of the farthest point, as well as the Lipschitzian dependence of this point on a point in space, we obtain necessary and su.cient conditions for the strong convexity of a set in several infinite-dimensional spaces, in particular, in a Hilbert space. A set representable as the intersection of closed balls of a fixed radius is called a strongly convex set. We show that the condition “for each point in space that is sufficiently far from a set, there exists a unique farthest point of the set” is a criterion for the strong convexity of a set in a finite-dimensional normed space, where the norm ball is a strongly convex set and a generating set.     

粗糙直觉模糊集的近似表示

在粗糙直觉模糊集的基础上,从新的角度提出了不确定目标概念的近似表示和处理的方法(通过近似模糊集和近似精确集刻画).首先将已有的直觉模糊集相似概念和均值直觉模糊集概念引入到该模型,定义了Pawlak近似空间U/R下的阶梯直觉模糊集、0.5-精确集的概念,然后得到了均值直觉模糊集(0.5-精确集)是所有直觉模糊集中与目标直觉模糊集最接近的直觉模糊集(近似精确集),接着分析了均值直觉模糊集、0.5-精确集分别与目标直觉模糊集的相似度随着知识粒度变化的变化规律.     

Vague集上模糊熵的几点注记

V ague集上的不确定性度量有两种途径,一种是度量V ague集是模糊集的程度,一种是度量V ague集具有的模糊性的程度。后者将模糊集的模糊熵作为特例。本文基于“投票模型”分析了V ague集的熵应具有的特征,对国内作者提出的V ague集上的模糊熵进行了评述。     

Computability of Self-Similar Sets

We investigate computability of a self-similar set on a Euclidean space. A nonempty compact subset of a Euclidean space is called a self-similar set if it equals to the union of the images of itself by some set of contractions. The main result in this paper is that if all of the contractions are computable, then the self-similar set is a recursive compact set. A further result on the case that the self-similar set forms a curve is also discussed.     

Uniqueness of non-Archimedean entire functions sharing sets of values counting multiplicity

A set is called a unique range set for a certain class of functions if each inverse image of that set uniquely determines a function from the given class. We show that a finite set is a unique range set, counting multiplicity, for non-Archimedean entire functions if and only if there is no non-trivial affine transformation preserving the set. Our proof uses a theorem of Berkovich to extend, to non-Archimedean entire functions, an argument used by Boutabaa, Escassut, and Haddad to prove this result for polynomials

     

拓扑空间子集的最小开集和最大闭集

讨论对于拓扑空间子集A是否存在包含A的最小开集和是否存在包含于A的最大闭集问题,证明了拓扑空间X是一个T1空间之充分且必要条件是,对于X的每一个子集A,X中存在包含A的最小开集（存在包含于A的最大闭集）当且仅当A是X的开集（闭集）,同时给出几个例子说明了定理的条件.     

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...     

Completions of Pseudo Ordered Sets

Order - A pseudo ordered set (X,≤) is a set X with a binary relation ≤ that is reflexive and antisymmetric. We associate to a pseudo ordered set X, a partially ordered set Γ(X)...     

点集映射的半连续性与Pareto有效点集的连通性

在研究多目标规划的有效解集的连通性时，许多文献通过将集合的有效点集表示为某个连通集上闭的点集映射的象集以得到结果．本文通过反例说明了连通集上闭的点集映射的象集未必是连通集，从而揭示了多目标规划有效解集连通性研究中存在的问题．据此，借助于点集映射的上半连续性，本文给出了集合的Pareto有效点集和Pareto弱有效点集的另一形式的连通性结果．     

Separation of clones of cooperations by cohyperidentities

An n-ary cooperation is a mapping from a nonempty set A to the nth copower of A. A clone of cooperations is a set of cooperations which is closed under superposition and contains all injections. Coalgebras are pairs consisting of a set and a set of cooperations defined on this set. We define terms for coalgebras, coidentities and cohyperidentities. These concepts will be applied to give a new solution of the completeness problem for clones of cooperations defined on a two-element set and to separate clones of cooperations by coidentities.     

Cookie-Cuter集的多重Fractal分解的Packing维数

直线上的Ｃｏｏｋｉｅ－Ｃｕｔｔｅｒ集是一个扩张动力系统的不变集，并且是一个Ｆｒａｃｔａｌ集合．本文得到Ｃｏｏｋｉｅ－Ｃｕｔｔｅｒ集的多重Ｆｒａｃｔａｌ分解的Ｐａｃｋｉｎｇ维数，从而证明其是Ｔａｙｌｏｒ意义下的Ｆｒａｃｔａｌ集合     

Subdifferential properties of the minimal time function of linear control systems

We present several formulae for the proximal and Fréchet subdifferentials of the minimal time function defined by a linear control system and a target set. At every point inside the target set, the proximal/Fréchet subdifferential is the intersection of the proximal/Fréchet normal cone of the target set and an upper level set of a so-called Hamiltonian function which depends only on the linear control system. At every point outside the target set, under a mild assumption, proximal/Fréchet subdifferential is the intersection of the proximal/Fréchet normal cone of an enlargement of the target set and a level set of the Hamiltonian function.     

共轭可交换性及其在集合形式单调类定理中的应用

引入了集列的极限运算与二元集运算之间的共轭可交换性的概念,讨论了常见的和重要的集列的极限运算与集代数运算之间所具有的共轭可交换性质,在一般的情形下证明了共轭可交换性是集类的极限运算生成类对集代数运算具有封闭性的一个充分条件,使得集合形式的单调类定理的理论得到了统一的解释,并且证明更简单,思路更清晰,最后还给出了一个新的集合形式的单调类定理.     

On analogs of spectral decomposition of a quantum state

The set of quantum states in a Hilbert space is considered. The structure of the set of extreme points of the set of states is investigated and an arbitrary state is represented as the Pettis integral over a finitely additive measure on the set of vector states, which is a generalization of the spectral decomposition of a normal state.     

关于格的极小生成元集

本文证明了格的极小生成元集一定是最小生成元集且只能是非零完全并既约元全体，证明了分配格具有最小生成元集的必要条件是它满足并无限分配律．本文还证明了完全Ｈｅｙｔｉｎｇ代数具有最小生成元集当且仅当它是强代数格，证明了完备格是强代数格当且仅当它和它的对偶格均是具有最小生成元集的分配格．     

锥有效拟凹集的有效点集的连通性

本文引进了锥有效拟凹集的概念，讨论了R ^m-严格拟凹与R ^m－有效拟凹的关系，证明了一个紧集为锥有效拟凹且其有效点集为闭集时，这个有效点集是连通的。     

The isolated invariant sets of a flow

Some definitions such as m-chain recurrent set, weakly gradient flow and generalized Morse decomposition for a flow defined on a topological space are introduced in this paper. Some conclusions, include the chain recurrent set contain the m-chain recurrent set; the m-chain recurrent set contain the non-wandering set, are proved. In some flows the non-wandering set is proper subset of the m-chain recurrent set; in the meantime the m-chain recurrent set is proper subset of the chain recurrent set. Moreover some criterions for the existence of trajectories joining singular points and a necessary and sufficient condition of the weakly gradient flow are also given here. At last the generalized Morse decomposition of the invariant set are discussed in the paper.     

Galois connexion of a fuzzy subset

By their representation theorem, Negoita and Ralescu ‘identify’ a fuzzy set with a family of ordinary sets (levels). Here we ‘identify’ a fuzzy set with a Galois connexion between the boolean of a set and the valuation set. The two representations are closely connected.     

Representation of finite action large games

A large game can be formalized as a probability distribution on the set of players' characteristics or as a function from a measure space of players to the set of players' characteristics. Given a game as a probability distribution on the set of players' characteristics, a representation of that game is a function from a set of players to the set of players' characteristics which induces the same distribution. It is shown that if the playoffs are continuous and there are only finite number of actions, then the set of Nash equilibria of any representation of a game induces essentially all the Cournot-Nash equilibrium distributions of the given game.     

可数Fuzzy紧集的性质

讨论可数Fuzzy紧集在L值Zadeh型函数下的逆不变性,证明可数Fuzzy紧集与Fuzzy紧集的乘积是可数Fuzzy紧的。