关于环Fpm+uFpm+u2Fpm上循环码的注记

本文研究了环F_p^m+uF_p^m+u²F_p^m上长度为p^s的循环码分类.通过建立环F_p^m+uF_p^m+u²F_p^m到环F_p^m+uF_p^m的同态,给出了环F_p^m+uF_p^m+u²F_p^m上长度为p^s的循环码的新分类方法.应用这种方法,得到了环F_p^m+uF_p^m+u²F_p^m长度为p^s的循环码的码词数.     

环Fp+vFp上互补对偶常循环码

本文研究了环F_p+vF_p上互补对偶（1-2v）-常循环码.利用环F_p+vF_p上（1-2v）-常循环码的分解式C=vC_1-v ⊕（1-v）C_v,得到了环F_p+vF_p上互补对偶（1-2v）-常循环码的生成多项式.然后借助从F_p+vF_p到F_p²的Gray映射,证明了环F_p+vF_p上互补对偶（1-2v）-常循环码的Gray像是F_p的互补对偶循环码.     

关于F2n中的和集

设F₂为两个元素组成的有限域, F₂ⁿ 为F₂上的n维向量空间. 对于集合A, B ⊆ F₂ⁿ , 它们的和集定义为所有两两互异的和a+b所组成的集合, 其中a∈A, b∈B. Green 和Tao 证明了: 设K > 1,如果A, B ? F₂ⁿ 且|A + B|≤K|A|^1/2|B|^1/2, 则存在一个子空间H?F₂ⁿ 满足
|H|>>exp(-O(√KlogK))|A|
以及x,y∈F₂ⁿ, 使得
|A∩(x+H)|^1/2|B∩(y+H)|^1/2≥1/2K|H|.
本文我们将使用Green 和Tao 的方法并作一些修改, 证明如果|H|>>exp(-O(√K))|A|,
则以上的结论仍然成立.     

一类有限阶可解完全群

It has been shown in the present paper that the automorphism group of the group of upper triangular matrices (a_ij) with entries in the finite field F_q(q=p^m,q>2, P is prime) and with α₁₁=1 is solvable and complete.     

一类具不变性质的变系数偏微分方程的特解

In this paper, a few properties of general patial differential operator P beinginvariant with respect to the form F(|x|_p^p+|y|_q^q-|z|_r^r) are studied, where x∈Rⁿ,y∈ R^m, z∈R^l.and explicit formulas are given for certain solution of the equation Pu=Aδ with P being a differential operator with power function coefficientswhich preserves the form (|x|_p^p+|y|_q^q-|z|_r^r)^1/v for arbitrary even integers p, q, r,and odd integers v.     

决定类数为一的(2,2,…,2)型代数函数域

设k=F_q(t)为F_q上以t为变元的有理函数域,F_q为q元域,特征不是2。设L=k(√D₁,…,√D_n~(1/2))是k的2ⁿ次扩张,常数域为F_q,D_i∈F_q[t],n>1。本文证明了:(1)除子类数为1的域L恰为k(√P₁,√P₂)和k(√P₁P₂,√P₁P₃),其中P_i∈F_q[t]为互异一次多项式。(2)理想类数为1的虚域L=k(√D₁,√D₂)(即L的整数环是唯一析因环)必是D₁=t;而D₂=t³-t-1(q=3),t²-t-1(q=3),t~2+2(q=5),或t+c,c∈F_q(或其在变换下的变形)。     

由分数次导数所确定的L2(T)中的一元周期函数类在Lq(T)中的相对宽度

作者研究了相对宽度K_n(W₂^α(T), MW₂^β(T), L₂(T)), T=[0,2π], 确定了使等式K_n(W₂^α(T), MW₂^β(T), L₂(T))=d_n(W₂^α(T), L₂(T))成立的最小M值, 得到了相对宽度K_n(W₂^α(T), W₂^α(T), L_q(T))的渐近阶, 其中α≥β>0, 1≤q≤∞, K_n(., ., L_q(T)) 和 d_n(., L_q(T))分别表示Kolmogorov意义下L_q(T)尺度下的相对宽度和宽度, MW_p^α(T), 1≤ p≤∞, 表示有如下卷积表达式的2π 周期函数类, f(t)=c+(B_α* g)(t),c∈ R, B_α*g 表示 B_α 和g 的卷积, g∈L_p(T) 满足∫₀^2πg(τ)dτ=0 和||g||_p≤M, B_α∈ L₁(T) 有如下Fourier展开: B_α(t)=1/2π∑' _{k∈ Z}(ik)^-αe^ikt,∑^'表示去掉 k=0的项.     

偶错位图的张量幂的最大独立集和自同构群

若A_n 是X := {1, 2,..., n} 上的偶置换构成的交错群, E_n 是X 上的偶错位集, 则Cayley 图AΓ_n := Γ(A_n, E_n) 称为偶错位图. 令AΓ_n^q 为q 个AΓ_n 的张量幂. 在本文中, 我们研究了AΓ_n^q 的连通性、直径、独立数、团数、色数和最大独立集等性质. 利用AΓ_n^q 最大独立集的结果, 我们完全确定了AΓ_n^q 的自同构群的结构.     

球上Zygmund 型空间上的加权Cesàro 算子

该文在Cⁿ中单位球上讨论了Zygmund 型空间(小Zygmund 型空间)之间的加权Cesàro 算子T_g 的有界性和紧性特征, 得到了以下的结果: (1) T_g 是Z^p 到Z^q的有界算子或紧算子的充要条件; (2) T_g 是 Z^p₀ 到Z^q₀ 的有界算子或紧算子的充要条件.     

Semiamart与Gaft类的收敛性

Let (Ω,F,P) be a probability space,(F_n) be an increasing sequence of sub-σ-fields of F, a sequence (x_n) of integrable random variables adapted to (F_n), if (x_n) is progressive uniformly integrable or(x_n)is a L¹-bounded Semiamart, then ( 1 ) x_m-x_n→0 (Pr.), ( 2 ) E (x_m|F_n)-x_n→0 (pr.) are equivalent is proved in this paper .     

有限域上的重根自对偶负循环码

Let F_q be a finite field with q = p~m, where p is an odd prime. In this paper, we study the repeated-root self-dual negacyclic codes over Fq. The enumeration of such codes is investigated. We obtain all the self-dual negacyclic codes of length 2~ap~r over F_q, a ≥ 1.The construction of self-dual negacyclic codes of length 2~abp~r over F_q is also provided, where gcd(2, b) = gcd(b, p) = 1 and a ≥ 1.     

有限域上一类负循环码

设F_q为一个阶为q的有限域,其中q为奇数.本文研究了x~n+1在F_q上的不可约分解及环F_q[x]/x~n+1中所有本原幂等元,这里的n是素因子整除q-1的某些正整数.进一步,得到了F_q上所有长度为n的不可约负循环码的检验多项式及极小汉明距离.     

A class of negacyclic BCH codes and its application to quantum codes

In this paper, we study negacyclic BCH codes over \(\mathbb {F}_{q}\) of length \(n=(q^{2m}-1)/(q-1)\), where q is an odd prime power and m is a positive integer. In particular, the dimension, the minimum distance and the weight distribution of some negacyclic BCH codes over \(\mathbb {F}_{q}\) of length \(n=(q^{2m}-1)/(q-1)\) are determined. Two classes of negacyclic BCH codes meeting the Griesmer bound are obtained. As an application, we construct quantum codes with good parameters from this class of negacyclic BCH codes.     

Negacyclic duadic codes

This paper extends the concepts from cyclic duadic codes to negacyclic codes over F_q (q an odd prime power) of oddly even length. Generalizations of defining sets, multipliers, splittings, even-like and odd-like codes are given. Necessary and sufficient conditions are given for the existence of self-dual negacyclic codes over F_q and the existence of splittings of 2N, where N is odd. Other negacyclic codes can be extended by two coordinates in a way to create self-dual codes with familiar parameters.     

Negacyclic codes over Galois rings of characteristic 2 a

We investigate negacyclic codes over the Galois ring GR(2 a ,m) of length N = 2 k n,where n is odd and k 0.We first determine the structure of u-constacyclic codes of length n over the finite chain ring GR(2 a ,m)[u]/ u 2 k + 1 .Then using a ring isomorphism we obtain the structure of negacyclic codes over GR(2 a ,m) of length N = 2 k n (n odd) and explore the existence of self-dual negacyclic codes over GR(2 a ,m).A bound for the homogeneous distance of such negacyclic codes is also given.     

CYCLIC AND NEGACYCLIC CODES OF LENGTH 2p^s OVER Fp^m ＋ uFp^m

In this article, we focus on cyclic and negacyclic codes of length 2p^s over the ring R = Fp^m ＋ uFp^m, where p is an odd prime. On the basis of the works of Dinh （in J.Algebra 324,940-950,2010）, we use the Chinese Remainder Theorem to establish the algebraic structure of cyclic and negacyclic codes of length 2p^s over the ring Fp^m ＋ uFp^m in terms of polynomial generators. Furthermore, we obtain the number of codewords in each of those cyclic and negacyclic codes.     

环GR(4,2)上一类负循环码的Gray象

研究了GR(4,2)上长为2~s的负循环码的Gray象,证明了GR(4,2)上长为2~s的负循环码的Gray象是F_4上长为2~(s+2)指数为2的准循环码.通过计算GR(2~a,m)上长为2~s的负循环码的齐次距离,确定了GR(4,2)上长为2~s的负循环码的Gray象的汉明距离.     

Z4上偶长度的LCD负循环码

线性互补对偶(LCD)码是一类重要的纠错码,在通信系统、数据存储以及密码等领域都有重要的应用.文章研究了整数模4的剩余类环Z₄上偶长度的LCD负循环码,给出了这类码的生成多项式,证明了这类码是自由可逆码;并且利用Z₄上偶长度负循环码构造了一类Lee距离至少为6的LCD码.     

一类代数几何码的构造

利用有限域Fq^8(s≥1为正整数，q为素数幂)上代数曲线构造了一类q元线性码，这类线性码是q^8元几何Goppa码的子域子码的子码，同时也是Chaoping Xing，SanLing构造的代数几何码[1]的推广。     

偶特征有限正交空间中的几个计数公式及应用

设Fq(n)是Fq上的n维正交空间,设P是任一个给定的m维全奇异子空间.计算了F(qn)中满足dim(P∩Q)=i的r维全奇异子空间Q的个数,给出了用子空间构作认证码的例子.