Interlacing of zeros of shifted sequences of one-parameter orthogonal polynomials

We study the interlacing property of zeros of Laguerre polynomials of adjacent degree, where the free parameters differ by an integer, and of the same degree, where the free parameter is shifted continuously. Similar interlacing results are proven for the positive zeros of Gegenbauer polynomials. Research by Kathy Driver is supported by the National Research Foundation of South Africa under grant number 2053730. Research by Kerstin Jordaan is partially supported by the National Research Foundation of South Africa under grant number 2054423.     

三角函数有理式积分技巧

结合实际例子给出四种处理三角有理式积分的技巧与方法,即利用对称性积分法、递推公式法、组合积分法、利用留数法.     

Generalization of a theorem of Kusmin

A Gauss-Kusmin theorem for the natural extension of the regular continued fraction expansion is given. A generalization of a theorem by D. E. Knuth is obtained by similar techniques.With 3 FiguresResearch of the first author supported by the Netherlands Organization of Scientific Research (NWO).     

一类Hamilton系统的Abel积分比值单调性的判别条件

用直接计算的方法对一类Hamilton系统的两个Abel积分比值的单调性进行讨论,指出该单词性条件可由两个判定函数直接确定．     

A graph-theoretic proof of the non-existence of self-orthogonal Latin squares of order 6

The non-existence of a pair of mutually orthogonal Latin squares of order six is a well-known result in the theory of combinatorial designs. It was conjectured by Euler in 1782 and was first proved by Tarry in 1900 by means of an exhaustive enumeration of equivalence classes of Latin squares of order six. Various further proofs have since been given, but these proofs generally require extensive prior subject knowledge in order to follow them, or are ‘blind’ proofs in the sense that most of the work is done by computer or by exhaustive enumeration. In this paper we present a graph-theoretic proof of a somewhat weaker result, namely the non-existence of self-orthogonal Latin squares of order six, by introducing the concept of a self-orthogonal Latin square graph. The advantage of this proof is that it is easily verifiable and accessible to discrete mathematicians not intimately familiar with the theory of combinatorial designs. The proof also does not require any significant prior knowledge of graph theory.     

Classification of dicoverings

The dicoverings of a “well pointed” d-space are classified as quotients of the universal dicovering space under congruence relations. We prove that the subcategory of d-spaces generated by the subcategory of directed cubes is equal to the category generated by the interval and the directed interval. Similarly, the category of topological spaces generated by simplices may be generated by the interval.     

Reduction of continuous symmetries of chaotic flows by the method of slices

We study continuous symmetry reduction of dynamical systems by the method of slices (method of moving frames) and show that a ‘slice’ defined by minimizing the distance to a single generic ‘template’ intersects the group orbit of every point in the full state space. Global symmetry reduction by a single slice is, however, not natural for a chaotic/ turbulent flow; it is better to cover the reduced state space by a set of slices, one for each dynamically prominent unstable pattern. Judiciously chosen, such tessellation eliminates the singular traversals of the inflection hyperplane that comes along with each slice, an artifact of using the templates local group linearization globally. We compute the jump in the reduced state space induced by crossing the inflection hyperplane. As an illustration of the method, we reduce the SO (2) symmetry of the complex Lorenz equations.     

膨胀土分类的一种新方法

在专家凭经验无法准确地确定评价指标的权重时,用相似系数确定权重,给出了一种新的多指标综合评价方法.将该方法应用于膨胀土的胀缩等级分类,其合理性和有效性得到了验证.     

Unimodularity of zeros of self-inversive polynomials

We generalise a necessary and sufficient condition given by Cohn for all the zeros of a self-inversive polynomial to be on the unit circle. Our theorem implies some sufficient conditions found by Lakatos, Losonczi and Schinzel. We apply our result to the study of a polynomial family closely related to Ramanujan polynomials, recently introduced by Gun, Murty and Rath, and studied by Murty, Smyth and Wang as well as by Lalín and Rogers. We prove that all polynomials in this family have their zeros on the unit circle, a result conjectured by Lalín and Rogers on computational evidence.     

Radius of convexity of certain classes of analytic functions

We consider the classes of analytic functions introduced recently by K.I. Noor which are defined by conditions joining ideas of close-to-convex and of bounded boundary rotation functions. We investigate coefficients estimates and radii of convexity.     

Magic of centroids

In this paper, we show some properties of centroids of geometric figures, such as triangles, quadrilaterals and tetrahedra. In particular, we will prove the properties by means of geometric transformations and by introducing extensions of triangles and quadrilaterals, i.e. by adding one, two or three new vertices to the figure. The study of these properties can be used, with profit, in a classroom activity supported by a dynamic geometry system.     

灰色关联分析方法在机场风险评价中的应用

本文通过对机场风险因素的分析,建立了一套合理的机场风险评价指标体系,并运用模糊层次分析法确定各评价指标的权重,然后结合灰色关联分析,建立了机场风险评价模型.最后将此方法运用到具体的实例中,说明了该方法的有效性.     

Polynomial approximation of functions with given order of thekth generalized modulus of smoothness

The problem of approximation by algebraic polynomials is considered on function classes characterized by the value of thekth generalized modulus of smoothness defined by the Jacobi generalized shift operator. Translated fromMatematicheskie Zametki, Vol. 63, No. 3, pp. 425–436, March, 1998.     

蛙卵有丝分裂模型的分岔分析

定性分析了Borisuk和Tyson建立的蛙卵有丝分裂模型,讨论了其定态的存在性和稳定性,深入研究了该模型的分岔行为并通过数值实验加以证实。此外,还给出了Tyson数值结果的理论依据。     

非系统风险的回报率及其计量

现代金融理论认为,系统风险无法通过组合投资进行规避,承担系统风险被市场承认从而可以获得风险报酬;非系统风险可以通过组合投资进行有效分散,因而承担非系统风险不应获得风险回报.试图阐述系统风险完全可以规避,指出承担非系统风险也应获得风险报酬,给出计量非系统风险回报率的规划方法,该规划的最优解同样满足两基金分离定理.     

一类哈密顿系统的Abel积分之比单调性的判据

研究了一类哈密顿系统的两个Abel积分比值的单调性的条件,指出这个单调性条件可由文中给出的两个判定函数直接确定.     

Embeddings of general blowups of abelian surfaces

Blowups of algebraic surfaces polarized by tensor powers of ample line bundles were studied by Coppens [8]. In this note we complete the picture in the case of abelian surfaces studying blowups of surfaces polarized by primitive line bundles. Received: 16 November 1999 / Revised version: 13 June 2000     

制造商与销售商双向选择与利益分配

分别建立制造商和销售商主导的供应链的利润分配模型,阐明为什么制造商和销售商都努力使自己成为供应链的主导企业,说明销售商主导型供应链竞争存在优势的原因.制造商主导的供应链中,制造商通过决定产品的批发价格最优化自身的利润分配;在销售商主导的供应链中,销售商通过决定批量折扣率达到对产品批发价格的控制,为销售商带来更大的利润.制造商和销售商在各自主导供应链的利润分配均大于供应链总体利润最大时的利润平均分配.给出一个具体的算例验证模型的结论.