Several new infinite families of NMDS codes with arbitrary dimensions supporting $t$-designs
Yaozong Zhang, Dabin Zheng, Xiaoqiang Wang, Wei Lu
TL;DR
This paper advances NMDS codes by constructing two infinite families over $\mathbb{F}_q$ with lengths $q+1$ and $q+2$ and arbitrary dimension, plus two families over $\mathbb{F}_{2^m}$ that support $2$- and $3$-designs; it provides explicit weight distributions and shows how the minimum-weight structures yield $t$-designs via the Assmus–Mattson framework. The methods combine carefully chosen generator matrices with subset-sum counting to control dual distances and weight enumerators, leveraging Vandermonde-type determinants and the Li–Wan formulas for finite-field subset sums. The main contributions are the first infinite families with arbitrary dimensions supporting $t$-designs (for $t\ge 2$) and an affirmative resolution of Heng-Wang’s conjecture on flexible NMDS codes for $2$-designs, together with concrete examples and comparisons to prior fixed-dimension constructions. These results enrich the design-theoretic applications of NMDS codes and open avenue toward higher-design-strength families, with potential implications for combinatorial design, finite geometry, and cryptographic constructions.
Abstract
Near maximum distance separable (NMDS) codes, where both the code and its dual are almost maximum distance separable, play pivotal roles in combinatorial design theory and cryptographic applications. Despite progress in fixed dimensions (e.g., dimension 4 codes by Ding and Tang \cite{Ding2020}), constructing NMDS codes with arbitrary dimensions supporting $t$-designs ($t\geq 2$) has remained open. In this paper, we construct two infinite families of NMDS codes over $\mathbb{F}_q$ for any prime power $q$ with flexible dimensions and determine their weight distributions. Further, two additional families with arbitrary dimensions over $\mathbb{F}_{2^m}$ supporting $2$-designs and $3$-designs, and their weight distributions are obtained. Our results fully generalize prior fixed-dimension works~\cite{DingY2024,Heng2023,Heng20231,Xu2022}, and affirmatively settle the Heng-Wang conjecture \cite{Heng2023} on the existence of NMDS codes with flexible parameters supporting $2$-designs.
