关于求线性规划初始可行基的生成算法

本文用反例证明了文「１」提出的求线性规划寝可行基的生成算法有错误,并给出了修正的生成算法。     

Grobner基的一个应用

固定一个项序,利用Buchberger算法求多项式环S=C[x1,x2,…,xn]上的理想I的Grbner基.根据S上任意多项式f（x1,x2,…,xn）用Grobner基表示时其余项唯一的特点,将其应用到求解多项式方程组问题.实例展示用Grobner基可证明一个联立方程式是无解的.     

基于亏基的最陡边主元标算法

在最陡边规则的基础上建立了新的主元标规则,并将其应用到亏基情形,在亏基的框架下建立了一个新的求对偶可行基的算法,数值结果表明,新算法能够减少迭代次数,算法效率较高,并且对于大规模问题的求解具有潜在优势,进一步表明了最陡边主元规则的可行性和有效性.     

线性规划分解筛选法的一个注记

[1][2]提出了求解线性规划问题的一种方法－分解筛选法,[3]证明了[2]的命题A是错误的,本进一步证明,用分解筛选法筛选出变量不一定是最优基变量。     

零化多项式的一个应用

利用矩阵的零化多项式 ,给出计算标准基解矩阵 e At的一个公式 .利用向量关于矩阵的零化多项式 ,给出常系数齐次线性微分方程组初值问题的一个求解公式 .相应地 ,可以推出常系数齐次线性差分方程组在给定的初始条件下的一个求解公式 .     

基于最钝角规则的亏基对偶单纯形Ⅰ阶段算法

对偶单纯形算法或原始对偶单纯形算法都需要一个初始对偶可行基．就此目的而言，基于最钝角行主元规则的对偶Ⅰ阶段算法非常有效[15].本文将其思想应用于亏基情形，建立一个不含比值检验的新的亏基对偶Ⅰ价段算法．初步的数值实验表明，该算法可在总体上减少运行时间和迭代次数，极具竞争性．     

线性规划约束方程系数矩阵的敏感性分析

本文首先给出了用当前基解和系数矩阵A的行(或列)增向量直接计算新基解及其检验数的一个简单公式,进而讨论了关于线性规划系数矩阵A的一行(列)向量变化的敏感性分析问题。给出了保持最优基不变时ΔA的变化范围。     

求基可行解一种概率意义下的多项式算法

本文对求线性规划问题的基可行解，给出一种改型算法，证明它对m个约束、n个变量的问题，当n≥2m时，为使求得一个基可行解的概率大于0．98，对m>24，所需迭代次数不超过（m＋3），而对m≥76，迭代次数已不超过（m＋1）．     

单边单项式序下的SAGBI基

设K是一个域,R是具有SM-基B的一个K-代数,且是B上一个单边（即左或右）单项式序.那么关于交换多项式代数和非交换自由代数的子代数在双边单项式序下经典的SAGBI基理论可完整地推广到R的子代数上来.特别地,对于一类N-分次代数,存在计算有限n-截断SAGBI基的有效算法,并且第一次阐明了在单边单项式序下讨论SAGBI...     

关于矩阵方程A^m=λJ

设A是n阶整数矩阵,J是所有元素为1的矩阵,矩阵方程A~m=λJ(1.1)的求解及解的分类是一个相当困难的问题。Ryser,Lam,Wang等人研究上述问题,给出了方程(1.1)的几类g-循环解。为了进一步研究方程的解,我们首先引入方程(1.1)基的概念。     

多重超平面完备残差图

本文研究了任意维超平面完备残差图和多重超平面完备残差图,将Erd¨os、Harary和Klawe’s定义的平面残差图推广到任意维超平面.利用容斥原理以及集合的运算性质等方法,获得了任意维超平面完备残差图的最小阶和唯一极图,以及任意维超平面完备残差图的一个重要性质,同时获得了多重任意维超平面完备残差图的最小阶和唯一极图.     

The Extraction Degree of Cale Monoids

The extraction degree measures commonality of factorization between any two elements in a commutative, cancellative monoid. Additional properties of the extraction degree are developed for monoids possessing a Cale basis. For block monoids, the complete set of extraction degrees is calculated between any two elements, between any two irreducible elements, and between any irreducible element and any general element.     

On geometrically transitive Hopf algebroids

This paper contributes to the characterization of a certain class of commutative Hopf algebroids. It is shown that a commutative flat Hopf algebroid with a non zero base ring and a nonempty character groupoid is geometrically transitive if and only if any base change morphism is a weak equivalence (in particular, if any extension of the base ring is Landweber exact), if and only if any trivial bundle is a principal bi-bundle, and if and only if any two objects are fpqc locally isomorphic. As a consequence, any two isotropy Hopf algebras of a geometrically transitive Hopf algebroid (as above) are weakly equivalent. Furthermore, the character groupoid is transitive and any two isotropy Hopf algebras are conjugated. Several other characterizations of these Hopf algebroids in relation to transitive groupoids are also given.     

A short proof of existence of disjoint hypercyclic operators

We give a short proof of existence of disjoint hypercyclic tuples of operators of any given length on any separable infinite dimensional Fréchet space. Similar argument provides disjoint dual hypercyclic tuples of operators of any length on any infinite dimensional Banach space with separable dual.     

An approximate version of Sumner?s universal tournament conjecture

Sumner?s universal tournament conjecture states that any tournament on 2n−2 vertices contains a copy of any directed tree on n vertices. We prove an asymptotic version of this conjecture, namely that any tournament on (2+o(1))n vertices contains a copy of any directed tree on n vertices. In addition, we prove an asymptotically best possible result for trees of bounded degree, namely that for any fixed Δ, any tournament on (1+o(1))n vertices contains a copy of any directed tree on n vertices with maximum degree at most Δ.     

关于超曲面的切面公式及其应用

本文给出任意ｎ维超曲面上任意一点的超切面方程的简洁的统一求法，将曲面方程微分即得切面方程．此法侧重对微分本质的理解，不需死记任何公式，计算简便．本文还讨论了此方法的理论意义，分别列举了到各种类型曲面的应用．     

阶数不超过4的交叉超立方体是点可迁的

P Kulasinghe and S Bettayeb showed that any multiply-twisted hypercube with five or more dimensions is not vertex-transitive. This note shows that any multiply-twisted hypercube with four or less dimensions is vertex-transitive, and that any multiply-twisted hypercube with three or larger dimensions is not edge-transitive.     

On the Spectra of Striped Sign Patterns

Sign patterns consisting of some positive and some negative columns, with at least one of each kind, are shown to allow any self-conjugate spectrum, and thus to allow any inertia. In the case of the n ×n sign pattern with all columns positive, given any self-conjugate multiset consisting of n -1 complex numbers supplemented by a sufficiently large positive number, it is shown how to construct a positive normal matrix whose spectrum is this multiset. Thus, the positive sign pattern allows any inertia with at least one positive eigenvalue.     

On the Spectra of Striped Sign Patterns

Sign patterns consisting of some positive and some negative columns, with at least one of each kind, are shown to allow any self-conjugate spectrum, and thus to allow any inertia. In the case of the n × n sign pattern with all columns positive, given any self-conjugate multiset consisting of n m 1 complex numbers supplemented by a sufficiently large positive number, it is shown how to construct a positive normal matrix whose spectrum is this multiset. Thus, the positive sign pattern allows any inertia with at least one positive eigenvalue.     

Gröbner bases of balanced polyominoes

We introduce balanced polyominoes and show that their ideal of inner minors is a prime ideal and has a squarefree Gröbner basis with respect to any monomial order, and we show that any row or column convex and any tree‐like polyomino is simple and balanced.