自正交拉丁方存在性的一个简短证明

本文是欧拉猜想的一个简明反证.文中给出了所有n≠2,3,6阶的一族自正交拉丁方. §1.引言 1959年和1960年,Bose,Shrikhande和Parker反证了欧拉关于不存在4t+2阶正交拉丁方的猜想,解决了正交拉丁方的存在性问题.1973年Brayton,Coppersmith     

矩阵方幂序列{A^k}的通项公式

文[1]、[2]对特征根满足λ_1~m=λ_2~m=…=λ_n~m的n阶矩阵方幂序列给出了通项公式,但未能给出一般矩阵方幂序列的通项公式,本文试图解决这一问题。 本文约定:A=(a_(ij))是实方阵,E是与A同     

溃坝问题的间断有限元方法

本文研究90年代初提出的Runge-Kutta间断Galerkin有限元方法，给出该方法的精度分析，通过经典算例验证该方法处理间断问题、捕捉锐利波形的能力，并将其推广到求解浅水问题．针对坝底无摩擦，无坡度的理想情形进行讨论，给出方溃坝和圆溃坝问题的数值模拟结果．     

关于Zd中离散填充指标的注记

探讨了Z^d中离散填充指标的一些性质，给出了Z^d中离散填充维数的一个等价定义．     

岭估计优于最小二乘估计的条件

本文讨论在均方误差意义下岭估计优于最小二乘估计的问题，给出了岭估计优于小最小二乘估计的必要条件及较一般的充分条件。     

正交拉丁方组和泛对角线幻方的一种构造法

利用线性取余变换构造素数阶完备正交拉丁方组,给出泛对角线幻方的一种构造法.     

超立方机上一阶线性递推问题的并行求解

本文考察解一阶线性递推问题的三个并行算法在超立方机上的实现方案.通过给出原始数据与超立方机之间的适当的映射以及算法执行过程中数据的通讯方式,奇偶消元法、奇偶约简法和变间距二分法都可以在起立方机上有效地执行.文中给出了这些算法的复杂性结论.最后,为进一步减少通讯费用,我们提供了一种复杂性更小的新算法,其通讯时间是与问题规模无关的常数.     

半参数回归模型的一类压缩估计

研究了半参数回归模型的参数估计问题,利用压缩估计方法给出了模型的一类有偏估计,并与最小二乘估计、岭估计、几乎无偏岭估计进行了比较.在均方误差意义下,新的压缩估计明显优于最小二乘估计.最后讨论了有偏参数选取的问题.     

分层随机抽样中R的联合比估计量的可用性及均方误差的估计量

本文从一个实际课题出发给出了分层随机抽样中R的联合比估计量五。的偏倚B(R_c)和均方误差MSE(R_c)的表达式,证明了估计量R_c是可用的,并给出了MSE(R_c)的估计量与MSE(R_c)的主要部分的偏倚的阶。最后列出了一些实际的计算结果。     

再谈n阶矩阵m次方幂的通项公式

文[1]曾给出一类n阶矩阵的方幂的通项公式,但只限于矩阵A(或A~k)全部特征根相等的情形。本文给出另一类n阶矩阵即A(或a~k)全部不同特征根为两个的分解定理,并在分解定理的基础上给出这类n阶矩阵的方幂的通项     

Metric inequalities for routings on direct connections with application to line planning

We consider multi-commodity flow problems in which capacities are installed on paths. In this setting, it is often important to distinguish between flows on direct connection routes, using single paths, and flows that include path switching. We derive a feasibility condition for path capacities supporting such direct connection flows similar to the well-known feasibility condition for arc capacities in ordinary multi-commodity flows. The condition can be expressed in terms of a class of metric inequalities for routings on direct connections. We illustrate the concept on the example of the line planning problem in public transport and present an application to large-scale real-world problems.     

Characterizations of Chain Conditions on Finite Matrix Subgroups

We give several characterizations of Zimmermann's uniform chain condition on matrix subgroups. In particular, we prove that a family of modules satisfies it precisely when the direct sum of their pure injective envelopes splits in their direct product. We also prove that a weaker non-uniform version of this condition is equivalent to Σ-algebraic compactness of reduced products.     

Determinimg abelian p-groups from their n-Socles

A necessary condition is given for a very wide separable p-group to be derermined by its n-socle (the set of elements of order at most p ⁿ). A group G is very wide if it has a direct summand of final rank ‖G‖ which itself is a direct sum of cyclic groups. In the case, n=1 (as Shelat has shown)this condition is sufficient but for n>1 examples are given to show that this condition is not sufficient.     

The mode of a probability mass function

A simple, direct condition is formulated for determining the mode(s) of a probability mass function. This condition is then applied to the Poisson and hypergeometric mass functions.     

关于条件极值充分条件的重新推导和证明

李文学用拉格朗日函数提出求条件极值的充分条件,但他的证明却是错误的.本文不用拉格朗日函数,而是直接通过消去一个变量将条件极值转化成无条件极值,重新推导出充分性条件.推导的过程也是条件极值充分条件的证明过程.     

Duality in the problems of optimal control described by first-order partial differential inclusions

On the basis of the apparatus of locally conjugate mappings, a sufficient condition for optimality is derived for the non-convex problem and duality theorems are proved. A sufficient condition for an extremum is an extremal relation for the direct and dual problem.     

The primal mixed finite element method and the LBB condition

Spurious or kinematic modes have posed a major obstacle to the implementation of the mixed finite element method. This research shows that spurious modes resulting from the approximation spaces not satisfying the LBB condition do not prevent a well posed problem. When the LBB condition is not satisfied, the resulting matrix equations are singular. A direct solution method is presented for the efficient solution of the possibly singular equations. Orthogonal flux basis functions are introduced to simplify the problem. Then the solution procedure is based on nested domain decomposition. This solution procedure is shown to be competitive with direct solution methods for the displacement finite element method. Examples are included to demonstrate various aspects of the LBB condition and the solution procedure.     

Algebraische Kompaktheit bei Faktorgruppen von Gruppen ganzzahliger Abbildungen

The complete direct sum modulo the direct sum of copies of ? fails to be algebraically compact as soon as the indexing set is uncountable. On the other hand, a sufficent condition is given to ensure algebraic compactness of certain smaller homomorphic images.     

集值优化问题在有效意义下的最优性条件

本文在赋范空间中,讨论集值优化问题的有效元导数型最优性条件.当目标映射和约束映射的下方向导数存在时,在近似锥次类凸假设下利用有效点的性质和凸集分离定理得到了集值优化问题有效元导数型Kuhn-Thcker必要条件,在可微Г-拟凸性的假设下得到了Kuhn-Tucker最优性充分条件;此外利用集值映射沿弱方向锥的导数的特性给出了有效解最优性的另一种刻画.     

Stability of Einstein-Hermitian vector bundles

Einstein-Hermitian vector bundles are defined by a certain curvature condition. We prove that over a compact Kähler manifold a bundle satisfying this condition is semistable in the sense of Mumford-Takemoto and a direct sum of stable Einstein-Hermitian subbundles.