图G_n的优美表示

将给出三个结果:(i)如果图G是SZ(|S|=n≥2)上的整数和图,那么0∈S当且仅当图G至少有一个(n-1)度顶点;(ii)图G(G≠K2)是至少有两个零点的整数和图当且仅当G■K2·Gn;(iii)设图G(G≠K2)是SZ上的整数和图,|S|=n+2,n∈N+.若图G至少有两个零点,则S={mx|m=-1,0,1,2,…,n;x∈Z且x≠0}.     

c-圈图的Laplace谱半径和最大度

设G是一个n阶的简单连通图,符号(d_1,d_2,...,d_n)表示G的度序列,其中d_1≥d_2≥···≥d_n,用符号?(G)表示G的最大度,而符号λ(G)表示G的Laplace谱半径.一个c-圈图是一个恰有n+c-1条边的n阶简单连通图,而符号C(n,?;c)表示最大度等于?的所有n阶c-圈图的集合.本文确定了当0≤c≤1/2(?-1)(?-2)时,C(n,?;c)中所有取得最小Laplace谱半径的极图,并分别确定了当?≥[n+2/3]且d_4≥2或?≥[n/3]+1且d_4=1时,C(n,?;1)中唯一取得最大Laplace谱半径的极图.进一步地,还证明了对于两个n阶的单圈图G和G′,如果?(G)≥[11n/30]+2且?(G)?(G′),则λ(G)λ(G′),并且界"[11n/30]+2"是最佳的.     

图的上可嵌入性与圈中顶点度

本文利用非上可嵌入图的充要条件,结合圈中顶点最大度与图的上可嵌入性之间的关系,得到了下两个结果:(1)设G是2-边连通简单图,若对G中任意圈G,存在点x∈C满足,d(x)>|V(G)|/3 1,则图G是上可嵌入的,且不等式的下界是不可达的.(2)设G={x,y;E}为简单二都图,且是2-边连通的. |x|=m,|Y|=n(m,n≥3),若对G中任意圈C,存在点x∈C且x∈X满足d(x)>n/3 1,则图G是上可嵌入的,且不等式的下界是不可达的.     

恰有两个主特征值的图的性质

设λ是图G的一个特征值,如果存在属于λ的一个特征向量X=(x_1,x_2,…,x_n)~T,使得(?)x_i≠0,则λ称为图G的主特征值.将恰有两个主特征值的一个充要条件做了进一步推广,并在此基础上给出恰有两个主特征值的图的一些性质以及恰有两个主特征值的图的一些运算结果.     

关于几乎唯一泛圈图

设G是阶为n的简单Hamilton图．若存在m(3(?)m＜n)使对每个l∈{3,4,…,n} -{m},G恰有一个长为l的圈且不含长为m的圈,则称G是几乎唯一泛圈图,用(?)k表示具有n k条边和恰有1/2(k 1)(k 2)个圈的简单H图的集合,用(?)_k~*表示具有n k条边恰有2~k k个圈的简单外可平面H图的集合,本文确定了(?)_k和(?)_k~*中所有几乎唯一泛圈图,并证明这些图都是简单MCD图,本文还构造了50个含有同胚于K_4的子图的几乎唯一泛圈图,并提出了若干问题和猜想。     

均衡二部图中点不交的4-圈和6-圈（英文）

设G=(V_1,V_2,E)是一个均衡二部图满足|V_1|=|V_2|=n.令δ_(1,1)(G)=min{d(x)+d(y)|x∈V_1,Y∈V_2}.Amar猜想对任意的s个整数(n_1,n_2,…,n_s),n=n_1+n_2+…+n_s,其中n_i≥2.若δ_(1,1)(G)≥n+s,则G含s个点不交的圈,其长分别为2n_1,2n_2,…,2n_s(见[Discrete Math.,1986,58(1):1-10]).本文证明了若一个点数为4k的均衡二部图G满足δ_(1,1)(G)≥2k+4(k≥3),则G含k-3个4-圈和2个6-圈使得所有这些圈都是点不交的.     

一类几乎唯一泛圈图

设G是阶为n的简单Hamilton图．若存在m(3(?)m相似文献   

关于完全t部图的色唯一性

设P(G,λ)是图的色多项式。如果对任意使P(G,λ)=P(H,λ)的图H都与G同构,则称图G是色唯一图.这里通过比较t 1色类的色划分数目,讨论了由Koh和Teo在文献[1]中提出的问题(若|ni-nj|≤2,当min(n1,n2,…,nt)充分大时,完全t部图K(n1,n2,…,nt)是否是色唯一图?)。改进了文献[5]中的结果。证明了若Σ1≤i≤ta2i=T,min{n a1,n a2,…,nt at,n-1}≥(T 1)/2,则K(n a1,n a2,…,n at)是色唯一图(其中ai是实数,n ai是正整数)。从而证明了若|ni-nj|≤k(i,j=1,2,…,t),min{n1,n2,…,nt}≥tk2/8 1,则K(n1,n2,…,nt)是色唯一图。     

关于图中子图的（n,k）—正交因子分解

设G是一个具有顶点集V(G)和边集E(G)的图. 设g和f是定义在V(G)上的两个整数值函数,使得g(x)f(x)对所有的点x∈V(G)都成立.如果G是一个(mg+n,mf-n)-图,1n<m2k,且g(x)2k-1对所有的点x∈V(G)都成立,则对任意给定具有|E(H)|=nk边的G的子图H,存在G的一个子图G′使G′有一个(g,f)-因子分解(n,k)-正交H.     

K_(2,3)的多重多部图设计的构造

λKn(t)是一个λ重完全多部图,G为一个不带孤立点的简单图.所谓的图设计G-HDλ(tn)是一个序偶(X,B),其中X是Kn(t)的顶点集,B为λKn(t)的一些子图(亦称为区组)构成的集合,使得任一区组均与图G同构,且λKn(t)的任意2个不同点组成的边恰在B的λ个区组中出现.本文讨论了G=K2,3的完全多部图设计存在性问题,证明了存在G-HDλ(tn)当且仅当λn(n-1)t2≡0(mod12),n≥2,nt≥5且(n,,λt)≠(9,1,1),(12,1,1),(3,1,2),(4,1,2).     

RECENT PROGRESS ON SPHERICAL HARMONIC APPROXIMATION MADE BY BNU RESEARCH GROUP ——In memory of Professor Sun Yongsheng

As early as in 1990, Professor Sun Yongsheng, suggested his students at Beijing Normal University to consider research problems on the unit sphere. Under his guidance and encouragement his students started the research on spherical harmonic analysis and approximation. In this paper, we incompletely introduce the main achievements in this area obtained by our group and relative researchers during recent 5 years （2001-2005）. The main topics are： convergence of Cesaro summability, a.e. and strong summability of Fourier-Laplace series; smoothness and K-functionals; Kolmogorov and linear widths.     

Instructions for Authors

<正>Submission Authors must use LaTeX for typewriting,and visit our website www.actamath.com to submit your paper.Our address is Editorial Office of Acta Mathematica Sinica,Academy of Mathematics and Systems Science,Chinese Academy of Sciences,Beijing 100190,P.R.China.     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

正August 10-14,2015Beijin,China The International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists     

Boundedness for commutators of multipliers on Hardy type spaces

In this paper, we study the commutators generalized by multipliers and a BMO function. Under some assumptions, we establish its boundedness properties from certain atomic Hardy space Hb^p（R^n） into the Lebesgue space L^p with p 〈 1.     

A unified approach to certain problems of best local approximation

In this paper we study best local quasi-rational approximation and best local approximation from finite dimensional subspaces of vectorial functions of several variables. Our approach extends and unifies several problems concerning best local multi-point approximation in different norms.     

Towards Excellence in Science Chinese Academy of Sciences

<正>May 26,2014,Beijing Science is a human enterprise in the pursuit of knowledge.The scientific revolution that occurred in the 17th Century initiated the advances of modern science.The scientific knowledge system created by     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

<正>August 10-14,2015Beijing,ChinaThe International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists     

Bounds for the zeros of polynomials

Let P(z)=∑↓j=0↑n ajx^j be a polynomial of degree n. In this paper we prove a more general result which interalia improves upon the bounds of a class of polynomials. We also prove a result which includes some extensions and generalizations of Enestrǒm-Kakeya theorem.