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Main Authors: Hegedüs, Gábor, Suda, Sho, Xiang, Ziqing
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.11461
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author Hegedüs, Gábor
Suda, Sho
Xiang, Ziqing
author_facet Hegedüs, Gábor
Suda, Sho
Xiang, Ziqing
contents For a code $C$ in a space with maximal distance $n$, we say that $C$ has symmetric distances if its distance set $S(C)$ is symmetric with respect to $n / 2$. In this paper, we prove that if $C$ is a binary code with length $2n$, constant weight $n$ and symmetric distances, then \[ |C| \leq \binom{2 n - 1}{|S(C)|}. \] This result can be interpreted using the language of Johnson association schemes. More generally, we give a framework to study codes with symmetric distances in Q-bipartite Q-polynomial association schemes, and provide upper bounds for such codes. Moreover, we use number theoretic techniques to determine when the equality holds.
format Preprint
id arxiv_https___arxiv_org_abs_2501_11461
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Codes with symmetric distances
Hegedüs, Gábor
Suda, Sho
Xiang, Ziqing
Combinatorics
For a code $C$ in a space with maximal distance $n$, we say that $C$ has symmetric distances if its distance set $S(C)$ is symmetric with respect to $n / 2$. In this paper, we prove that if $C$ is a binary code with length $2n$, constant weight $n$ and symmetric distances, then \[ |C| \leq \binom{2 n - 1}{|S(C)|}. \] This result can be interpreted using the language of Johnson association schemes. More generally, we give a framework to study codes with symmetric distances in Q-bipartite Q-polynomial association schemes, and provide upper bounds for such codes. Moreover, we use number theoretic techniques to determine when the equality holds.
title Codes with symmetric distances
topic Combinatorics
url https://arxiv.org/abs/2501.11461