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A generalization of multi-twisted codes over finite fields, their Galois duals and Type II codes
Journal of Applied Mathematics and Computing ( IF 2.2 ) Pub Date : 2021-06-14 , DOI: 10.1007/s12190-021-01574-1
Varsha Chauhan , Anuradha Sharma

Let \(\mathbb {F}_q\) denote the finite field of order q, and let \(\Lambda =(\lambda _1,\lambda _2,\cdots ,\lambda _\ell ),\) where \(\lambda _1,\lambda _2,\cdots ,\lambda _\ell \) are non-zero elements of \(\mathbb {F}_q.\) Let \(n =m_1+m_2+\cdots +m_\ell ,\) where \(m_1,m_2,\cdots ,m_\ell \) are arbitrary positive integers (not necessarily coprime to q). In this paper, we study algebraic structures of \(\Lambda \)-multi-twisted (\(\Lambda \)-MT) codes of length n and block lengths \((m_1,m_2,\cdots ,m_{\ell })\) over \(\mathbb {F}_q\) and their Galois duals (i.e., their orthogonal complements with respect to the Galois inner product on \(\mathbb {F}_{q}^n\)). We develop generator theory for \(\Lambda \)-MT codes of length n over \(\mathbb {F}_{q}\) and show that each \(\Lambda \)-MT code of length n over \(\mathbb {F}_{q}\) has a unique nice normalized generating set. With the help of a normalized generating set, we explicitly determine the dimension and a generating set of the Galois dual of each \(\Lambda \)-MT code of length n over \(\mathbb {F}_{q}.\) We also provide a trace description of all \(\Lambda \)-MT codes of length n over \(\mathbb {F}_{q}\) by using the generalized discrete Fourier transform (GDFT), which gives rise to a method to construct these codes. We further provide necessary and sufficient conditions under which a Euclidean self-dual \(\Lambda \)-MT code of length n over \(\mathbb {F}_{2^e}\) is a Type II code when \(\lambda _i=1\) and \(m_i = n_i2^a\) for \( 1\le i \le \ell ,\) where \(a \ge 0\) is an integer and \(n_1, n_2, \cdots , n_{\ell }\) are odd positive integers satisfying \(n_1 \equiv n_2 \equiv \cdots \equiv n_{\ell }~ (\text {mod }4).\) Besides this, we obtain several linear codes with best-known and optimal parameters from 1-generator \(\Lambda \)-MT codes over \(\mathbb {F}_{q},\) where \(2 \le q \le 7.\) It is worth mentioning that these code parameters can not be attained by any of their subclasses (such as constacyclic and quasi-twisted codes) containing record breaker codes.



中文翻译:

有限域上多扭码的推广、它们的伽罗瓦对偶和类型 II 码

\(\ mathbb {F} _q \)表示顺序的有限域q,并让\(\ LAMBDA =(\拉姆达_1,\拉姆达_2,\ cdots,\拉姆达_ \ ELL),\)其中\( \lambda_1,\lambda_2,\cdots,\lambda_\ell\)\(\mathbb {F}_q.\)的非零元素让\(n =m_1+m_2+\cdots +m_\ell , \)其中\(m_1,m_2,\cdots ,m_\ell \)是任意正整数(不一定与q互质)。在本文中,我们研究了\(\Lambda \) -multi-twisted ( \(\Lambda \) -MT) 长度为n和块长度\((m_1,m_2,\cdots ,m_{\ell })\)结束\(\mathbb {F}_q\)和它们的伽罗瓦对偶(即它们关于\(\mathbb {F}_{q}^n\)上的伽罗瓦内积的正交补集)。我们开发发生器理论\(\ LAMBDA \) -MT长度的码Ñ超过\(\ mathbb {F} _ {Q} \) ,并显示每个\(\ LAMBDA \) -MT长度的代码Ñ超过\( \mathbb {F}_{q}\)有一个独特的好的归一化生成集。用的归一化发电机组的帮助下,我们明确地确定尺寸和每个所述伽罗瓦双重的发电机组\(\ LAMBDA \) -MT长度的代码Ñ超过\(\ mathbb {F} _ {Q}。\ )我们还通过使用广义离散傅立叶变换 (GDFT)提供了所有长度为n 的\(\Lambda \) -MT 代码在\(\mathbb {F}_{q}\) 上的轨迹描述,这产生了构造这些代码的方法。我们进一步提供了充分必要条件,在该条件下,长度为n超过\(\mathbb {F}_{2^e}\)的欧几里得自对偶\(\Lambda \) -MT 代码是类型 II 代码,当\( \lambda _i=1\)\(m_i = n_i2^a\)对于\( 1\le i \le \ell ,\)其中\(a \ge 0\)是一个整数,而\(n_1, n_2, \cdots , n_{\ell }\)是奇数正整数满足\(n_1 \equiv n_2 \equiv \cdots \equiv n_{\ell }~ (\text {mod }4).\)除此之外,我们从1-generator \( \Lambda \) -MT 代码超过\(\mathbb {F}_{q},\) where \(2 \le q \le 7.\)值得一提的是,这些代码参数无法通过任何它们的子类(例如恒环和准扭曲代码)包含破纪录的代码。

更新日期:2021-06-15
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