当$4q^{5}-5q^{4}-2q+1\leq d \leq 4q^{5}-5q^{4}-q$时$[g_{q}(6,d),6,d]_{q}$码的不存在性

证明了对于q≥17,当4q~5-5q~4-2q+1≤d≤4q~5-5q~4-q时,不存在达到Griesmer界的[n,k,d]_q码.此结果推广了Cheon等人在2005年和2008年的非存在性定理.     

关于超立方体网络的(d,k)独立数

(d,k)独立数是分析互连网络性能的一个重要参数.对于任意给定的图G和正整数d和k,确定G的(d,k)独立数问题是一个NPC问题.因此,确定一些特殊图的(d,k)独立数显得很重要.本文确定了k维超立方体网络的(d,k)独立数等于2,如果d=k≥4或者d=k-1≥6 以及αd,k-t(Qk)=αd,k(Qk),其中0≤t≤k-2,1≤d≤k-t-1.     

Maximal Dimension of Invariant Subspaces to Systems of Nonlinear Evolution Equations

In this paper,the dimension of invariant subspaces admitted by nonlinear systems is estimated under certain conditions.It is shown that if the two-component nonlinear vector differential operator F=(F 1,F 2) with orders {k 1,k 2 } (k 1 ≥ k 2) preserves the invariant subspace W 1 n 1 × W 2 n 2 (n 1 ≥ n 2),then n 1 n 2 ≤ k 2,n 1 ≤ 2(k 1 + k 2) + 1,where W q n q is the space generated by solutions of a linear ordinary differential equation of order n q (q=1,2).Several examples including the (1+1)-dimensional diffusion system and Ito 's type,Drinfel'd-Sokolov-Wilson's type and Whitham-Broer-Kaup's type equations are presented to illustrate the result.Furthermore,the estimate of dimension for m-component nonlinear systems is also given.     

图的k部划分的一个注记

设k≥2是一个整数。本文证明了任意有m条边的图都存在一个顶点的划分V_1,V_2…,V_k,使得e(V_1,V_2…,V_k)≥k-1/k m+k-1/2k((2m+1/4)~1/2-1/2)-(k-2)~2/8k,且max{e(V_i):1≤i≤k}≤m/k~2+(k-1)/2k~2((2m+1/4)~1/2-1/2+3/8-7k-4/8k~2.我们的结果改进了[Fan G.,Hou J.,Zeng Q.,A bound for judicious k-partitions of graphs,Discrete Appl.Math.,2014,179:86—99]的主要结论.     

关于D.H.Lehmer问题与超级Kloosterman和

设整数q>2,c与q互素．对于1到q之间与q互素的任意整数a,在1到q之间存在唯一的整数b满足ab≡c mod q．对任意整数k≥2,定义M(q,k,c)为满足1≤ai≤q, (ai,q)=1,i=1,2,…,k,a1a2…ak≡c mod q且2 a1 a2 … ak的正整数组(a1,a2,…,ak)的数目,并设E(q,k,c)=M(q,k,c)-(φk-1(q))/2．本文的主要目的是利用Gauss和与原特征的性质,以及Dirichlet L-函数的均值定理,来研究E(q,k,c)与超级Kloosterman和K(h,k,q)的混合均值,并给出一个均值公式．     

混合幂的除数和（英文）

令S_k(x)=∑d(n_1~2+n_2~2+n_3~k),3≤k∈N.1≤n_1,n_2≤x~(1/2)1≤n_3≤x~(1/k)本文得到了渐近公式S_k(x)=A(k)x~(1+1/k)logx+B(k)x~(1+1/k)+O(x~(1+1/k-δ(k)+ε)),这里A(k),B(k)是只与k有关的常数,δ(3)=5/(42),δ(4)=1/(16),δ(5)=1/(40),并且当6≤k≤7时δ(k)=1/(k2~(k-1)),当k≥8时δ(k)=1/(2k~2(k-1)).     

The Criticality for Circular Coloring of Graph

For two positive integers k and d such that k ≥ 2d, Gkd is the graph with vertex set{0,1,…,k-1} in which ij is an edge if and only ifd ≤ |i-j|≤ k-d. Clearly, Gk1 is acomplete graph of k vertices and we always assume d ≥ 2 in the following.     

The Criticality for Circular Coloring of Graph G_d~k

For two positive integers k and d such that k ≥ 2d, Gkd is the graph with vertex set {0,1, ...,k-1} in which ij is an edge if and only if d ≤ |i-j| ≤ k-d. Clearly, Gk1 is a complete graph of k vertices and we always assume d ≥ 2 in the following. It is easy to see (also [1]) that a graph G is (k, d)-colorable if and only if there exists a homomorphism from G to Gkd.     

超立方体网络的(d,k)控制数

(d,k)控制数是刻画容错网络中资源共亨可靠性的一个新参数.本文考虑了k维超立方体Qk的(d,k)控制数,得到:γ1,k(Qk)=2k-1(k>1);d=[k/2] 1(k>2)时,γd,k(Qk)=2;d≤[k/2](k≥4)时,3≤γd,k(Qk)≤2k-d 1;以及若d为正整数,且[k/d]=[k/(d-1)] 1,则γd,k(Qk)=γd,k(Qk),其中[k/d].d 1≤k1≤k.     

关于本原射影Reed-Solomon码的深洞

本原射影Reed-Solomon码是数字通信领域中的一类重要的极大距离可分码.在本原射影ReedSolomon码的译码过程中,人们通常采用极大似然译码算法.对于一个收到的向量u∈F_q~n,极大似然译码算法关键在于确定向量u关于码C的错误距离d(u,C).熟知d(u,C)≤ρ(C),其中ρ(C)为码C的覆盖半径.若d(u,C)=ρ(C),则称u为码C的深洞.本文得到了本原射影Reed-Solomon码PPRS_q(F_q~*,k)的一类深洞.实际上,利用有限域F_q上极大距离可分码的生成矩阵,本文证明如下结果成立:如果q≥4,整数k满足2≤k≤q-2,收到的向量u的前q-1个分量的Lagrange插值多项式为u(x)=λx~(q-2)+f≤k-2(x),其中λ∈F_q~*,f≤k-2(x)为F_q上次数不超过k-2的多项式,并且u的第q个分量为0,那么u是本原射影Reed-Solomon码PPRSq(F_q~*,k)的一个深洞.