一类基于m序列码的阵列码

通过对阵列 H码和 m序列码的分析 ,本文证明了阵列 H码中的一类正规 H码与 m序列码间的关系     

Artin局部主理想环上多项式理想的Grbner基的标准型

本文给出 Ａｒｔｉｎ局部主理想环上单变元多项式理想的极小Grbner基的标准型．证明 Ｎｅｃｈａｅｖ提出的标准生成系（ＣＧＳ）恰是极小 Ｇｒｏｂｎｅｒ基．将标准型用于分析环上线性码．     

纠错组码的一个界

给出了完全多部图覆盖与纠错组码的一种一一对应关系，从而利用Huang（1996）的一个结果给出了纠错组码的一个界，并利用仿射设计给出了使这个界的等号成立的一族线性码．     

环Z_4+vZ_4上的线性码:重量计数器及其Macwilliams恒等式

首先给出了环R=Z_4+vZ_4(v~2=v)上线性码的Gray映射及其投影映射的性质,得到了环R上线性码与通过投影映射得到的线性码的极小Lee重量的关系,然后定义了环R上线性码的Gray重量计数器和对称重量计数器,进一步地确定了环R上线性码与其对偶码之间关于Gray重量计数器,对称重量计数器和Lee重量计数器的MacWilliams恒等式.     

一类满分集酉空时码的构造

酉空时码特别适用于多天线差分调制的通信系统．本文基于两类适用于3天线系统的满分集的酉空时码给出了一个新的构造方案．由于新方案构造的酉空时码是满分集的,适用于天线数为奇素数的系统,而且与很多已知的码相比,具有更优的增益性能．     

代数几何码的测试

性质测试是90年代开始由多种研究引发的,GF（q）^n中一个线性码C称为局部可测试的,当且仅当存在一个随机化算法,使得只要输入任一个GF（q）^n中向量的很少一部分坐标（一般而言是常数个坐标）,这个随机化算法就可以很高的概率判定此向量是否是C中码字．Blum,Luby和Rubinfeld由于和概率可验证证明的紧密关系研究了码的局部可测试性,然而怎样刻画局部可测试码是一个复杂且甚具挑战性的问题．对Reed—Solomon（RS）码、Reed．Muller（RM）码、循环码、BCH码的对偶码及代数几何码的迹子码,已经研究了局部可测试问题．在本文中我们给出了代数几何码的线性参数的测试子,并证明了在一个不太强的限制条件下代数几何码不是局部可测试的．     

线性码译码的一种算法

线性码译码的一种算法杜宏（中国科学院系统科学研究所，北京１０００８０）１９９２年３月２５日收到．引言线性码的译码算法一直是一个公开问题．Ｊ．Ｊｕｓｔｅｓｅｎ等人在文［２］中给出了平面代数曲线上代数几何码译码的一种算法之后，Ａ．Ｎ．Ｓｋｏｒｏｂｏｇａｔ...     

结合一种新搜索的Broyden算法类的全局收敛性

文[1]给出了基本周期矩阵为对角形状的线性递归m-阵列的平移等价类的计数．本文在此基础上运用这表达式分别给出了：（1）具有任意一个可能的基本周期矩阵；（2）Grobner窗口为m×n；（3）Grobner窗口大小即级数为任意正整数w时的线性递归m-阵列不同平移等价类的个数．     

矩阵乘积码的自对偶码

Blackmore和Norton引入了矩阵乘积码的概念,并给出其对偶码的形式,但未涉及其自对偶码的研究.给出了存在矩阵使得构成的矩阵乘积码成为自对偶码的充分必要条件及其应用举例.     

关于设计距离为7的BCH码的非循环等价类

利用Mobius公式给出了设计距离为7的二元BCH码的非循环等价类的精确计数．     

Constructions of maximum distance separable symbol-pair codes using cyclic and constacyclic codes

Symbol-pair code is a new coding framework which is proposed to correct errors in the symbol-pair read channel. In particular, maximum distance separable (MDS) symbol-pair codes are a kind of symbol-pair codes with the best possible error-correction capability. Employing cyclic and constacyclic codes, we construct three new classes of MDS symbol-pair codes with minimum pair-distance five or six. Moreover, we find a necessary and sufficient condition which ensures a class of cyclic codes to be MDS symbol-pair codes. This condition is related to certain property of a special kind of linear fractional transformations. A detailed analysis on these linear fractional transformations leads to an algorithm, which produces many MDS symbol-pair codes with minimum pair-distance seven.     

On the Cyclicity of Goppa Codes,Parity-Check Subcodes of Goppa Codes,and Extended Goppa Codes

Classical Goppa codes are a special case of Alternant codes. First we prove that the parity-check subcodes of Goppa codes and the extended Goppa codes are both Alternant codes. Before this paper, all known cyclic Goppa codes were some particular BCH codes. Many families of Goppa codes with a cyclic extension have been found. All these cyclic codes are in fact Alternant codes associated to a cyclic Generalized Reed–Solomon code. In (1989, J. Combin. Theory Ser. A 51, 205–220) H. Stichtenoth determined all cyclic extended Goppa codes with this property. In a recent paper (T. P. Berger, 1999, in “Finite Fields: Theory, Applications and Algorithms (R. Mullin and G. Mullen, Eds.), pp. 143–154, Amer. Math. Soc., Providence), we used some semi-linear transformations on GRS codes to construct cyclic Alternant codes that are not associated to cyclic GRS codes. In this paper, we use these results to construct cyclic Goppa codes that are not BCH codes, new families of Goppa codes with a cyclic extension, and some families of non-cyclic Goppa codes with a cyclic parity-check subcode.     

New Linear Codes Over \mathbb{F}_3 and \mathbb{F}_5 and Improvements on Bounds

One of the most important problems of coding theory is to constructcodes with best possible minimum distances. In this paper, we generalize the method introduced by [8] and obtain new codes which improve the best known minimum distance bounds of some linear codes. We have found a new linear ternary code and 8 new linear codes over with improved minimumdistances. First we introduce a generalized version of Gray map,then we give definition of quasi cyclic codes and introduce nearlyquasi cyclic codes. Next, we give the parameters of new codeswith their generator matrices. Finally, we have included twotables which give Hamming weight enumerators of these new codes.     

An efficient algorithm for constructing reversible quasi-cyclic codes via Chinese remainder theorem

Regarding quasi-cyclic codes as certain polynomial matrices, we show that all reversible quasi-cyclic codes are decomposed into reversible linear codes of shorter lengths corresponding to the coprime divisors of the polynomials with the form of one minus x to the power of m. This decomposition brings us an efficient method to construct reversible quasi-cyclic codes. We also investigate the reversibility and the self-duality of the linear codes corresponding to the coprime divisors of the polynomials. Specializing to the cases where the number of cyclic sections is not more than two, we give necessary and sufficient conditions for the divisors of the polynomials for which the self-dual codes are reversible and the reversible codes of half-length-dimension are self-dual. Our theorems are utilized to search reversible self-dual quasi-cyclic codes with two cyclic sections over binary and quaternary fields of lengths up to seventy and thirty-six, respectively, together with the maximums of their minimum weights.     

Three-dimensional cyclic Fire codes

Three-dimensional cyclic array codes over F _q that can correct single three-dimensional bursts (or clusters) of errors are considered. The class cyclic three-dimensional burst-error-correcting array codes, called three-dimensional Fire codes, is constructed. Several important properties such as the burst-error-correcting capability and the positions of the parity-check symbols are presented. Also, encoding and decoding algorithms are given.     

Constructions of Sidon spaces and cyclic subspace codes

In this paper, we firstly construct several new kinds of Sidon spaces and Sidon sets by investigating some known results. Secondly, using these Sidon spaces, we will present a construction of cyclic subspace codes with cardinality τ · $\frac{{{q^n} - 1}}{{q - 1}}$ and minimum distance 2k−2, where τ is a positive integer. We furthermore give some cyclic subspace codes with size 2τ · $\frac{{{q^n} - 1}}{{q - 1}}$ and without changing the minimum distance 2k−2.     

On generator and parity-check polynomial matrices of generalized quasi-cyclic codes

Generalized quasi-cyclic (GQC) codes have been investigated as well as quasi-cyclic (QC) codes, e.g., on the construction of efficient low-density parity-check codes. While QC codes have the same length of cyclic intervals, GQC codes have different lengths of cyclic intervals. Similarly to QC codes, each GQC code can be described by an upper triangular generator polynomial matrix, from which the systematic encoder is constructed. In this paper, a complete theory of generator polynomial matrices of GQC codes, including a relation formula between generator polynomial matrices and parity-check polynomial matrices through their equations, is provided. This relation generalizes those of cyclic codes and QC codes. While the previous researches on GQC codes are mainly concerned with 1-generator case or linear algebraic approach, our argument covers the general case and shows the complete analogy of QC case. We do not use Gröbner basis theory explicitly in order that all arguments of this paper are self-contained. Numerical examples are attached to the dual procedure that extracts one from each other. Finally, we provide an efficient algorithm which calculates all generator polynomial matrices with given cyclic intervals.     

Covering and radius-covering arrays: Constructions and classification

The minimum number of rows in covering arrays (equivalently, surjective codes) and radius-covering arrays (equivalently, surjective codes with a radius) has been determined precisely only in special cases. In this paper, explicit constructions for numerous best known covering arrays (upper bounds) are found by a combination of combinatorial and computational methods. For radius-covering arrays, explicit constructions from covering codes are developed. Lower bounds are improved upon using connections to orthogonal arrays, partition matrices, and covering codes, and in specific cases by computation. Consequently for some parameter sets the minimum size of a covering array is determined precisely. For some of these, a complete classification of all inequivalent covering arrays is determined, again using computational techniques. Existence tables for up to 10 columns, up to 8 symbols, and all possible strengths are presented to report the best current lower and upper bounds, and classifications of inequivalent arrays.     

AMDS symbol-pair codes from repeated-root cyclic codes

Symbol-pair codes are proposed to guard against pair-errors in symbol-pair read channels. The minimum symbol-pair distance is of significance in determining the error-correcting capability of a symbol-pair code. One of the central themes in symbol-pair coding theory is the constructions of symbol-pair codes with the largest possible minimum symbol-pair distance. Maximum distance separable (MDS) and almost maximum distance separable (AMDS) symbol-pair codes are optimal and sub-optimal regarding the Singleton bound, respectively. In this paper, six new classes of AMDS symbol-pair codes are explicitly constructed through repeated-root cyclic codes. Remarkably, one class of such codes has unbounded lengths and the minimum symbol-pair distance of another class can reach 13.