$2$-quasi-perfect Lee codes and abelian Ramanujan graphs: a new construction and relationship

TL;DR

This paper introduces a new family of 2-quasi-perfect Lee codes over finite fields and establishes a theoretical connection between these codes and abelian Ramanujan graphs, unifying two areas of combinatorial design.

Contribution

It provides an explicit construction of 2-quasi-perfect Lee codes and links them to well-known abelian Ramanujan graphs, expanding understanding of their relationship.

Findings

Constructed an infinite family of 2-quasi-perfect Lee codes for q ≥ 14.

Established a theoretical connection between Lee codes and abelian Ramanujan graphs.

Unified frameworks for Lee codes and Ramanujan graphs are developed.

Abstract

This paper presents a new explicit infinite family of 2-quasi-perfect $p$-ary Lee codes of length $\frac{q-1}{2}$ and dimension $\frac{q-1}{2}-2k$ for $q = p^k \ge 14$, $p\geq 5$ a prime. Our codes are derived from the generating set $H_q = \{(a, a^3) \mid a \in \mathbb{F}_q^*\}$ of the additive group of the finite field $\mathbb{F}_{q^2}$. Furthermore, we bridge between 2-quasi-perfect Lee codes constructed by Mesnager, Tang, and Qi and well-known abelian Ramanujan graphs, specifically Li's graphs and finite Euclidean graphs, providing a unified theoretical framework for these families.