有限p-群的幂结构

<正> 设G是有限p-群,n是正整数,记 V_n(G)={x~(pn)|x∈G},∧_n(G)={x∈G|x~(pn)=1}; (G)=,Ω_n(G)=<∧_n(G)>.又令下述性质: p_1:对任意正整数n,(G)=∨_n(G); p_2:对任意正整数n,Ω_n(G)=∧_n(G); P_3:对任意正整数n,|G:Ω_n(G)|=|(G)|. A.Mann在[1]中规定,如果G的每个部分群(即子群、商群和子群的商群的统称)都     

关于最佳通近问题的一个显式解

本短文给出在带权w(x)=(1-x~2)~(1/2)意义下最佳一致逼近问题的的显式解。众所周知,最佳逼近问题是逼近论中的重要课题。设T_n(x)=cos(narccosx),u_n(x)=sin((n+1)arccosx)/(1-x~2)~(1/2)分别是[-1,1]上第一,二类Chebyshev多项式,记π_n是首项系教为1的n次多项式全体,熟知: 对任何m_n(x)∈π_n.自然要问,对某些权w(x),是否可求出某P_n(x)∈π_n,使满足:     

AN INEQUALITY OF SCHUR''''S TYPE

It is proved that the Chebyshev polynomial _n(x)=T_n (xcos π/2n), has the greatest uniformnorm on [-1, 1] of its third derivative among the real polynomials of degree at most n, whichare bounded by 1 in [-1, 1] and vanish in -1 and 1.     

广义幂的Hausdorff矩量问题

§1引言Hausdorff曾研究过形如μ_n=∫_0~1(x~ndg(x) (n=0,1,2,…)的矩量问题,在那里多项式起着实质的作用(参见〔1〕)。术文的目的是利用广义多项式〔2〕〔3〕研究下列形状的矩量问题:μ_n=integral from 0 to 1x~(α_n)dg(x) (n=0,1,2,…),这里 α_n 不一定是整数。我们将采用〔4〕解决当 α_n 都是整数的问题时所用的方法。     

域上两类矩阵保逆的诱导映射

令F是一个域,S_n(F)是F上所有n×n上对称矩阵的集合.用T_n(F)记F上所有n阶上三角阵的集合.首先分别给出诱导映射和保逆性的定义.然后改进了关于复对称阵保逆的主要相关结果及其证明,得到了S_n(F)保逆诱导映射的一般形式,最后借助于类序列技术和初等方法刻画了T_n(F)保逆诱导映射.它推广和改进了带有附加条件(f_(ij)(x)=0x=0)的相关结果.     

方程x~((n))+f_1(t)x~((n-1))+f_2(t)x~((n-2))+…+f_(n-1)(t)■+f_n(t)x=0解的稳定性

考虑方程z~((n))+f_1(t)x~((n-1))+f_2(t)x~((n-2))+……+f_(n-1)(t)x+f_n(t)=0 (1)在现有文献中,对方程(1)的研究几乎能集中在二阶,对于 n>2的情形,很少见到。本文应用变换技巧以及.直接方法,特别利用文[9]的推广了的方法研究了 n 为任意正整数的方程(1)的平凡解的稳定性,得到了其平凡解全局一致渐近稳定性的充分条件。特别当 n=2时所得的结果包含了文献[1-8]的有关结果。有些结果就非文[8]的条件所能得到,如本文定理4、5及其推论1。     

广义Lipschitz伪压缩映射黏滞迭代逼近方法的强收敛

K是Banach空间E的一个非空闭凸子集,T:K→K是一个广义Lipschitz伪压缩映射.对Lipschitz强伪压缩映射f:K→K和x_1∈K,序列{x_n}由下式定义:x_n+1=(1-α_n-β_n)x_n+α_nf(x_n)+β_nTx_n.在{α_n}与{β_n}满足合适条件的情况下,每当{z∈K;μ_n‖x_n-z‖~2=inf_(y∈K)μ_n‖x_n-y‖~2}∩F(T)≠φ时,{x_n}强收敛到T的某个不动点x~*.     

关于重节点多元B样条的构造

1.引言 设x~0,x~1,…,x~n∈R~s是互异的点,n≥s,vol_s[x~0,…,x~n]>0,这里[x~0,…,x~n]={x=sum from j=0 to n(υ_jx~j|(υ_0,…,υ_n)∈S~n),S~n={(υ_0,…,υ_n)|sum from j=0 to n(υ_j=1,υ_j≥0,j=0,…,n}。 以x~i为m_i 1重节点,m_i≥0,i=0,…,n,的多元B样条M(x|(x~0)~(m_0 1),…,(x~n)~(m_n 1))由下式定义(见C.A.Micchelli[1]):     

Hermite-Fejer Interpolation With Moved End Points

Let Z_n={z_(kn)=cosθ_(kn):θ_(kn)=(2k-1)/(2n)π,k=1,2…,n}be the zeros of T_n(x)=cosnθ(x=cosθ,θ∈[0,π]).For 0≤ε≤1,let α_n=:α_n(ε)=:cos(1-ε)/(2n)π,β_n=:β_n(ε)=:cos(2n-1+ε)/(2n)π=-α_n,X_n~(1)=(Z_n-{z_(1z)})∪{α_n},X_n~(2)=(Zn-{z_(nn)})∪{β_n},X_n~(3)=(Z_n-{z_(1n),z_(nn)})∪{α_n,β_n},Y_n~(1)=Z_n∪{α_n},Y_n~(2)=Z_n∪{β_n},Y_n~(3)=Z_n∪{α_nβ_n}.     

高阶微分方程解的渐近性态

对高阶微分方程x~(n)+F(t,x,…,x~(n-1)=0及x~(n)+H_n(t,x~(n-1)+…+H_1(t,x)=f(t),本文得到了有解(?)x~(n-1)存在且不为零的的定理1、1＇,从而把文[1]、[2]、[3]在二阶微分方程的结果完善地推广到一般高阶微分方程。另外本文还得到了上面微分方程有解逼近方程 x~(n)=0的解的定理2,2＇。本文的推论证明本文定理1、1＇的条件是必要的.     

Estimation of the number of components of finite mixtures of multivariate distributions

An estimator of the number of components of a finite mixture ofk-dimensional distributions is given on the basis of a one-dimensional independent random sample obtained by a transformation of ak-dimensional independent random sample. A consistency of the estimator is shown. Some simulation results are given in a case of finite mixtures of two-dimensional normal distributions.     

Eigenvector p-Bases of Rings of Constants of Derivations

Let A be a UFD of characteristic p > 0, let 𝒵 be a set of some eigenvectors of a derivation of A. We prove, under some additional assumptions, a necessary and sufficient condition for 𝒵 to be a p-basis of the minimal ring of constants containing 𝒵. The main preparatory result is the unique decomposition theorem with respect to a factor from a given subalgebra containing A^p.     

Galois Structure of K-Groups of Rings of Integers

N/Kbe a Galois extension of number fields with finite Galois group G.We describe a new approach for constructing invariants of the G-module structure of the K groups of the ring of integers of N in the Grothendieck group of finitely generated projective Z[G]modules. In various cases we can relate these classes, and their function field counterparts, to the root number class of Fröhlich and Cassou-Noguès.     

有资格限制的指派问题的求解方法

在实际的指派工作中，常会遇到某个人有没有资格去承担某项工作的问题，因此，本建立了有资格限制的指派问题的数学模型。在此数学模型中，将效益矩阵转化为判定矩阵，由此给出了判定此种指派问题是否有解的方法；在有解的情况下，进一步将效益矩阵转化为求解矩阵，从而将有资格限制的指派问题化为传统的指派问题来求解。最后给出了一个数值例子来说明这样的处理方法是有效的。     

On Sums of Coefficients of Products of Polynomials

We study the nilpotency of the sums of all coefficients of some sorts of products of polynomials over reversible, IFP, and NI rings, and introduce an SCN ring as a generalization. We characterize SCN rings in relation with related ring properties, and also provide several useful properties and ring extensions of SCN rings.     

Convergence of sequences of sets of associated primes

It is a well-known result of M. Brodmann that if is an ideal of a commutative Noetherian ring , then the set of associated primes of the -th power of is constant for all large . This paper is concerned with the following question: given a prime ideal of which is known to be in for all large integers , can one identify a term of the sequence beyond which will subsequently be an ever-present? This paper presents some results about convergence of sequences of sets of associated primes of graded components of finitely generated graded modules over a standard positively graded commutative Noetherian ring; those results are then applied to the above question.

     

Rates of Convergence of Means of Euclidean Functionals

Let L be the Euclidean functional with p-th power-weighted edges. Examples include the sum of the p-th power-weighted lengths of the edges in minimal spanning trees, traveling salesman tours, and minimal matchings. Motivated by the works of Steele, Redmond and Yukich (Ann. Appl. Probab. 4, 1057–1073, 1994, Stoch. Process. Appl. 61, 289–304, 1996) have shown that for n i.i.d. sample points {X ₁,…,X _n } from [0,1] ^d , L({X ₁,…,X _n })/n ^(d−p)/d converges a.s. to a finite constant. Here we bound the rate of convergence of EL({X ₁,…,X _n })/n ^(d−p)/d . Y. Koo supported by the BK21 project of the Department of Mathematics, Sungkyunkwan University. S. Lee supported by the BK21 project of the Department of Mathematics, Yonsei University.     

Number of connected components of groups of real points of adjoint groups

We present a unified approach to compute the number of connected components in the group of real points of adjoint almost simple real algebraic groups.     

Enumeration of perfect matchings of a type of Cartesian products of graphs

Let G be a graph and let Pm(G) denote the number of perfect matchings of G.We denote the path with m vertices by P_m and the Cartesian product of graphs G and H by G×H. In this paper, as the continuance of our paper [W. Yan, F. Zhang, Enumeration of perfect matchings of graphs with reflective symmetry by Pfaffians, Adv. Appl. Math. 32 (2004) 175-188], we enumerate perfect matchings in a type of Cartesian products of graphs by the Pfaffian method, which was discovered by Kasteleyn. Here are some of our results:1. Let T be a tree and let C_n denote the cycle with n vertices. Then Pm(C₄×T)=∏(2+α²), where the product ranges over all eigenvalues α of T. Moreover, we prove that Pm(C₄×T) is always a square or double a square.2. Let T be a tree. Then Pm(P₄×T)=∏(1+3α²+α⁴), where the product ranges over all non-negative eigenvalues α of T.3. Let T be a tree with a perfect matching. Then Pm(P₃×T)=∏(2+α²), where the product ranges over all positive eigenvalues α of T. Moreover, we prove that Pm(C₄×T)=[Pm(P₃×T)]².