The Asymptotic Number of Anticodes in Hamming Spaces
Abstract
In the Hamming space π½qn, a d-anticode is a subset in which every pair of points has Hamming distance at most d, or equivalently, a set of diameter at most d. Let mq(n,d) denote the maximum size of a d-anticode and let πq(n,d) be the family of all d-anticodes. We show that for fixed q, as nββ, the total number of d-anticodes satisfies |πq(n,d)|=2(1+o(1))mq(n,d) for 4β€ dβ€ nβ1, except when q=2 and d=nβ1. We also count linear d-anticodes, that is, subspaces of π½qn with diameter at most d. For fixed q and d, their number is polynomial in n. For growing d, we determine the exponential order as qΞq(d2+dlogq(n/d)) in the sublinear regime and qΞ(n2) when d/nβΞ±β(0,1). In the near-full regime nβd=o(n), we obtain the sharper count q(1/4+o(1))n2. A random-generator construction further improves the binary lower bound for every fixed linear diameter.
Related
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BibTeX
@misc{horlemann2026asymptotic,
title = {{The Asymptotic Number of Anticodes in Hamming Spaces}},
author = {Anna-Lena Horlemann and Ananthakrishnan Ravi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31618},
eprint = {2610.31618},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31618},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Asymptotic Number of Anticodes in Hamming Spaces
AU - Anna-Lena Horlemann
AU - Ananthakrishnan Ravi
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31618
UR - https://arxiv.org/abs/2610.31618
AB - In the Hamming space π½_q^n, a d-anticode is a subset in which every pair of points has Hamming distance at most d, or equivalently, a set of diameter at most d. Let m_q(n,d) denote the maximum size of a d-anticode and let π_q(n,d) be the family of all d-anticodes. We show that for fixed q, as nββ, the total number of d-anticodes satisfies |π_q(n,d)|=2^(1+o(1))m_q(n,d) for 4β€ dβ€ nβ1, except when q=2 and d=nβ1. We also count linear d-anticodes, that is, subspaces of π½_q^n with diameter at most d. For fixed q and d, their number is polynomial in n. For growing d, we determine the exponential order as q^Ξ_q(d^2+dlog_q(n/d)) in the sublinear regime and q^Ξ(n^2) when d/nβΞ±β(0,1). In the near-full regime nβd=o(n), we obtain the sharper count q^(1/4+o(1))n^2. A random-generator construction further improves the binary lower bound for every fixed linear diameter.
ER -