Double circulant LCD codes over π½2+uπ½2 and constructions for binary LCD codes
Abstract
Linear complementary dual (LCD) codes are linear codes that intersect their dual trivially. We study double circulant (Euclidean) LCD codes over the finite chain ring R=π½2+uπ½2, where u2=0. Using the Chinese Remainder Theorem and the factorization of xnβ1, we derive an explicit enumeration formula, with a separate treatment of the constituent corresponding to xβ1, which is not obtained by a formal specialization of the previously known counting formula over π½q[u]/(uk). Assuming Artin's primitive root conjecture for $2$, we show that the binary Gray images contain an asymptotically good family of rate 1/2 whose relative distance can approach H2β1(1/4) from below. More importantly from the constructive viewpoint, by combining Gray images with a known extension construction, we obtain a binary LCD code with parameters $[29,15,7]$ and construct two explicit permutation-inequivalent binary LCD codes with parameters $[45,23,9]$.
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BibTeX
@misc{xu2026double,
title = {{Double circulant LCD codes over $\mathbbF_2+u\mathbbF_2$ and constructions for binary LCD codes}},
author = {Xingxing Xu and Minjia Shi and Jon-Lark Kim},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.16121},
eprint = {2610.16121},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.16121},
}
RIS
TY - UNPB
TI - Double circulant LCD codes over π½_2+uπ½_2 and constructions for binary LCD codes
AU - Xingxing Xu
AU - Minjia Shi
AU - Jon-Lark Kim
PY - 2026
DA - 2026/10/12
PB - arXiv
DO - 10.48550/arxiv.2610.16121
UR - https://arxiv.org/abs/2610.16121
AB - Linear complementary dual (LCD) codes are linear codes that intersect their dual trivially. We study double circulant (Euclidean) LCD codes over the finite chain ring R=π½_2+uπ½_2, where u^2=0. Using the Chinese Remainder Theorem and the factorization of x^nβ1, we derive an explicit enumeration formula, with a separate treatment of the constituent corresponding to xβ1, which is not obtained by a formal specialization of the previously known counting formula over π½_q[u]/(u^k). Assuming Artin's primitive root conjecture for $2$, we show that the binary Gray images contain an asymptotically good family of rate 1/2 whose relative distance can approach H_2^β1(1/4) from below. More importantly from the constructive viewpoint, by combining Gray images with a known extension construction, we obtain a binary LCD code with parameters $[29,15,7]$ and construct two explicit permutation-inequivalent binary LCD codes with parameters $[45,23,9]$.
ER -