几种类型的K~*空间的特征

<正> §1.引言 假设非平坦的 n 维黎曼空间的曲率张量 R_(hijk)在每一点恒满足下列关系(?)其中(?)是某一向量场,同时也满足     

L-fuzzy代数的刻画

鉴于[2]中已有fuzzy代数结合的不理想，谷文祥和卢荼在L－fuzzy集论中重新定义了L－fuzzy代数，得到了一些理想的结论。但却没有给出它的截集式刻画。本文的目的就是借助于L－fuzzy集的几种水平截集给出了它的几个等价刻画，使得它的表现更为直观且更便于应用。最后，作为应用，本文简洁地证明了L－fuzzy代数在代数同态下是不变的和逆不变的。     

伪投射模的特征

本文运用伪投射模刻划了半单环、左遗传环、完全环、半完全环、拟完全环和半局部环的性质和特征。     

马氏链集间转移的一类强大数定律

本文研究了马氏链从一个状态子集到另一个状态子集的转移概率的极限性质.利用Doob鞅收敛定理,获得了任意随机序列的强大数定律、马氏链泛函的强大数定律和强遍历定理.推广了马氏链传统转移概率的极限性质和强极限定理.     

直觉L模糊子群的刻画

本文研究了一个群G上的直觉L模糊子群.借助于L模糊集的截集,反模糊子群,得到了群G上的直觉L模糊子群的等价刻画.在直觉L模糊子群和群G上的子群族之间可以建立起一一对应.     

投射模的局部化特征

本文给出了对任何Ｐ，Ｑ∈Ｐ（Ｒ），Ｐｑ≌Ｑｑ，Ｖｑ∈ＳｐｅｃＲ当且发Ｐ≌Ｑ的充要条件，研究了半局部环，零维环等常见及其多项式环，幂级数环上投射模的局部化特征。     

CHARACTERIZATIONS OF SYMMETRIC MULTISTEP RUNGE-KUTTA METHODS

Some characterizations for symmetric multistep Runge-Kutta(RK) methods are obtained. Symmetric two-step RK methods with one and two-stages are presented. Numerical examples show that symmetry of multistep RK methods alone is not sufficient for long time integration for reversible Hamiltonian systems. This is an important difference between one-step and multistep symmetric RK methods.     

NEW SPECTRAL CHARACTERIZATIONS OF EXTREMAL HYPERSURFACES

Let M be a closed extremal hypersurface in Sn+1 with the same mean curva-ture of the Willmore torus Wm,n?m. We proved that if Specp(M)=Specp(Wm,n?m) for p=0, 1, 2, then M is Wm,m.     

TOPOLOGICAL CHARACTERIZATIONS OF THE EXTENDING PROPERTY OF RINGS

A commutative ring R is called extending if every ideal is essential in a direct summand of RR. The following results are proved： （1） C（X） is an extending ring if and only if X is extremely disconnected; （2） Spec（R） is extremely disconnected and R is semiprime if and only if R is a nonsingular extending ring; （3） Spec（R） is extremely disconnected if and only if R/N（R） is an extending ring, where N（R） consists of all nilpotent elements of R. As an application, it is also shown that any Gelfand nonsingular extending ring is clean.     

CHARACTERIZATIONS OF SOME MATRIX CLASSES OF QUASI-HOMOGENEOUS OPERATORS

In this paper,we give a general characterization of a class of matrices of quasi-homogeneous operators between topological vector spaces.     

（C—K）性质的特征

该文绘出（C－K），K=Ⅰ，Ⅱ，Ⅲ正性质的一些充要条件，从而我们得到：如果Banach空间X有（C一Ⅲ）（（C－Ⅱ）；（C－Ⅰ）性质，则对X的任意赋范集AU（X*），单位球面S（X）上的σ（X，A）拓朴与弱拓扑（范数拓扑）等价且X近非常凸（近强凸；强凸）.     

可数良紧集的刻画与性质

本文借助于α-序列,α-局部有限族及α∧--w聚点等概念给出了可数良紧集的一些等价刻画,进而讨论了可数良紧集在L值Zadeh型函数下的逆不变性,证明了可数良紧集与良紧集的乘只是可数良紧的。     

ANOTHER CHARACTERIZATION OF BICOREFLECTIVE SUBCATEGORIES

Abstract

In this paper, the relation between the notion of a discrete functor (see [4]) and the notion of a fine functor (see [1]) is examined. As a generalization of the notion of a F-fine object (see [1]), discrete functors T: A → X are used to define K-fine objects, where K is a class of A-objects. It is shown that if T is in addition semi-topological, then (as for F-fine objects in a topological category, see [1]) the class of K-fine objects determines a bicoreflective subcategory of A. Moreover, it is shown that in co-complete, co-(well-powered) categories, the existence of bicoreflective subcategories is equivalent to the existence of functors that are both discrete and semi-topological.     

正规软代数的性质与等价刻划

本文利用软代数的奇元、偶元、中性元及中理想等概念对正规软代数的性质进行了讨论，并给出了正规软代数的几种等价刻划。     

MULTIPLIERS OF SEGAL ALGEBRAS A_p(G)

Let G be a locally compact but non-compact abelian group,It is proved thatM(A_p(G),L_1(G))=M(G)and M(A_p(G),L_1(G)∩C_0(G))=M(L_1(G),L_1(G)∩C_0(G)).If G is discrete,then M(A_p(G),L_1(G))=A_p(G),M(A_p,(G),L_1(G)∩C_0(G))=A_p(G).     

Carleson测度与Bloch的刻画

在文中，对于C^n中有界强拟凸域。我们得到Carleson测度，消没Carleson测度的刻画。利用Carleson测度，我们还得到Bloch，小Bloch的刻画。     

多目标规划的ακ-较多有效解的几何特性

In this paper, with the help of properties of P-linear below bounded points, tangent cones, cone k-interior points, projective cones, the geometric char-acterizations of ακ-major efficient solutions and ακ-major optimality solutions of multiobjective programming are obtained.     

边界层形态的另一描述

利用Lions在Sobolev空间中的边界层理论和Pohozaev恒等式的一般形式和高阶形式,给出边界层形态的另一描述.     

不含 l_1-Copy 的空间的鞅特征

自从 Jamesc 将 Asplund 空间与不含 l_1-Copy 的空间明确地区分之后,划分两种空间界限的问题引起了广泛的兴趣。特别地,Riddle,Uhl 利用向量值鞅的某些性质很好地给出了两者之间的界限。本文在[1]的基础上,应用鞅和鞅型序列的某些性质进一步刻画了不 l_1-Copy 的空间的特征,从某些方面划分了 Asplund 空间与不含 l_1-Copy空间的界限(本文略去了 Asplund 空间情况的相应定理)。