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arXiv 2211.03392cs.ITmath.IT
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准循环码非零权重个数的紧上界

A tight upper bound on the number of non-zero weights of a quasi-cyclic code

Xiaoxiao Li, Minjia Shi, San Ling

AI总结:

本文研究准循环码非零权重个数的上界问题,通过分析自同构子群的轨道得到显式上界及达界充要条件,对一生成元准循环码给出更紧上界,并用实例验证其紧性,改进推广了已有结果。

摘要:

设$\u27e8\frak{C}\u27e9$为指数$l(l\neq2)$的准循环码。设$G$是$\u27e8\frak{C}\u27e9$自同构群中由$\rho^l$和$\u27e8\frak{C}\u27e9$的标量乘法生成的子群,其中$\rho$表示标准循环移位。本文中,我们得到了$G$在$\u27e8\frak{C}\u27e9\neq \{\mathbf{0}\}$上的轨道显式公式。由此,可直接推导出$\u27e8\frak{C}\u27e9$非零权重个数的显式上界,并给出了达到该上界的码的充要条件。若$\u27e8\frak{C}\u27e9$是一生成元准循环码,通过考虑由乘子、$\rho^l$和$\u27e8\frak{C}\u27e9$的标量乘法生成的更大自同构子群,可得到更紧的$\u27e8\frak{C}\u27e9$非零权重个数上界。我们特别列举了若干示例,证明这些上界是紧的。本文主要结果改进并推广了文献\textit{[M2]}中的部分结论。

英文摘要:

Let $\mathcal{C}$ be a quasi-cyclic code of index $l(l\geq2)$. Let $G$ be the subgroup of the automorphism group of $\mathcal{C}$ generated by $ρ^l$ and the scalar multiplications of $\mathcal{C}$, where $ρ$ denotes the standard cyclic shift. In this paper, we find an explicit formula of orbits of $G$ on $\mathcal{C}\setminus \{\mathbf{0}\}$. Consequently, an explicit upper bound on the number of nonzero weights of $\mathcal{C}$ is immediately derived and a necessary and sufficient condition for codes meeting the bound is exhibited. If $\mathcal{C}$ is a one-generator quasi-cyclic code, a tighter upper bound on the number of nonzero weights of $\mathcal{C}$ is obtained by considering a larger automorphism subgroup which is generated by the multiplier, $ρ^l$ and the scalar multiplications of $\mathcal{C}$. In particular, we list some examples to show the bounds are tight. Our main result improves and generalizes some of the results in \cite{M2}.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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