环上矩阵环的导子

文[1]讨论了除环上2阶全矩阵环的导子的一些性质,本文继此讨论一般结合环R上的R阶全矩阵环R_n的导子的性质.环R的加群自同态(?)称为R的导子,若对x、y∈R,有d(xy)=xd(y) d(x)y.如下总假定R有单位元,且用R_n表示R上的n阶全矩阵环,E_ij表示(i,j)位置元素为R的单位元1其余元素为零的R_n的矩阵单位,xE饰表示对角线上元素为x的数量阵.     

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.     

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2/3n+δ(n),则它必须是全测地的或微分同胚于Veronese曲面.     

一般ZPI－环的一个新刻划

设Ｒ是有单位元的交换，环则Ｒ是一般ＺＰＩ－环当且仅当Ｒ的每个同态象的全分式环都是主理想环．     

单位球中完备超曲面的一个刚性定理

本文研究了单位球中的数量曲率满足r=aH+b的完备超曲面的问题.利用极值原理的方法,获得了超曲面的一个刚性结果,推广了这一类具有常中曲率或者常数量曲率超曲面的结果.     

M_2(R)上的非线性Lie导子

设R是一个含有单位元的2无扰的交换环,M_2(R)是定义在R上的全矩阵代数,证明了M_2(R)上的每一个非线性Lie导子都可以表示成一个内导子,一个可加诱导导子和一个映所有二次换位子为零的中心映射的和.     

空间形式中常数量率的子流形

本文利用一个类似于Cheng和Yau引进的微分算子的新微分算子，得到了单位球面中常数量率的紧致子流形的一个刚性结果．     

全脐子流形的一个特征

１９７４年Ｍ．Ｏｋｕｍｕｒａ证明［１］：设Ｍｎ（ｎ≥３）为ｎ＋１维单位球面Ｓｎ＋１的紧致常平均曲率超曲面，若其第二基本形式的模长平方则Ｍｎ为全脐超曲面，其中Ｈ为平均曲率．本文目的是把限制常数改为，而且对于余维数大于１的情况也有类似的结果．     

全要素生产率和产业结构对能源利用影响的实证分析

本文利用能源消耗模型进行实证分析,结果表明决定能源利用效率的关键因素和长期因素是全要素生产率,全要素生产率的不断提高导致了我国经济快速发展而单位GDP能源消耗不断降低的特殊现象.产业结构对能源消耗有显著的短期影响,当第一产业比例下降或第二产业比例上升时,能源消耗增加。市场化程度、对外开放程度对能源消耗的作用体现在全要素生产率中.2000年后能源消耗重新抬头并不否定全要素生产率的作用,而是缺乏节能意识的负面影响抵消并逆转了全要素生产率的正面作用.     

二供应商经济批量问题的多项式时间算法

为了从采购费用结构不同的供应商中找到最佳补货策略,考虑一个零售商从两个供应商补货的二供应商经济批量问题.零售商在两个供应商处的采购费用结构分别为复合安装费用和全单位数量折扣费用结构.通过对问题结构性质的分析论证,将问题的可行解转化为一个有向网络,降低问题求解的计算复杂性.综合动态规划和Dijkstra最短路算法证明了该问题是多项式时间可解的.     

Sasakian子流形的谱几何

本文讨论了 Ｓａｓａｋｉａｎ子流形的谱几何,获得了复 Ｑｕａｄｒｉｃ上圆周丛以及全测地子流形的谱特征．     

球面上紧超曲面的等谱问题

本文讨论了球面上全脐超曲面与全测地超曲面的等谱问题。     

Independence of the Total Reflexivity Conditions for Modules

We show that the conditions defining total reflexivity for modules are independent. In particular, we construct a commutative Noetherian local ring R and a reflexive R-module M such that Ext_Rⁱ(M,R)=0 for all i>0, but Ext_Rⁱ(M^*,R)≠0 for all i>0. Presented by Juergen Herzog Mathematics Subject Classification (2000) 13D07.     

Slant and semi-slant submanifolds of a kenmotsu manifold

In the present note we have obtained some basic results pertaining to the geometry of slant and semi-slant submanifolds of a Kenmotsu manifold.      

全序幂等元剩余格

研究了全序幂等元剩余格,给出了全序幂等元剩余格的另一种新的构造方法,并且得到了这类剩余格的结构定理,推广了相关文献的结论．     

Full spark frames and totally positive matrices

In this paper we establish a connection between full spark frames and totally nonsingular matrices. Then we provide a method for constructing infinite totally positive matrices which make up a subclass of the class of totally nonsingular matrices. Using this method we then construct a family of infinite totally positive matrices parameterized by non-negative numbers which contains, as the simplest case, the infinite Pascal matrix. The paper ends with some examples and comments on full spark frames.     

The property of being algebraic for the lattice of all τ-closed totally saturated formations

It is proved that the lattice of all τ-closed totally saturated formations of finite groups is algebraic. __________ Translated From Algebra I Logika, Vol. 45, No. 5, pp. 620–626, September–October, 2006.     

Totally ordered sets and the prime spectra of rings

Let T be a totally ordered set and let D(T) denotes the set of all cuts of T. We prove the existence of a discrete valuation domain O_v such that T is order isomorphic to two special subsets of Spec(O_v). We prove that if A is a ring (not necessarily commutative), whose prime spectrum is totally ordered and satisfies (K2), then there exists a totally ordered set U?Spec(A) such that the prime spectrum of A is order isomorphic to D(U). We also present equivalent conditions for a totally ordered set to be a Dedekind totally ordered set. At the end, we present an algebraic geometry point of view.     

Real Hypersurfaces in Quaternionic Space Forms Satyisfying Axioms of Planes

A Riemannian manifold satisfies the axiom of 2-planes if at each point, there are suficiently many totally geodesic surfaces passing through that point. Real hypersurfaces in quaternionic space forms admit nice families of tangent planes, namely, totally real, half-quaternionic and quaternionic. Several definitions of axiom of planes arise naturally when we consider such families of tangent planes. We are able to classify real hypersurfaces in quaternionic space forms satisfying these definitions.     

Characterization of Totally Geodesic Totally Real 3-dimensional Submanifolds in the 6-sphere

In this paper, we study Lagrangian submanifolds of the nearly Kaehler 6-sphere. We derive a pinching result for the Ricci curvature of such submanifolds thus providing a characterisation of the totally geodesic submanifold. Our pinching result improves a previous result obtained by H. Li.