English

Forbidding Exactly One Hamming Distance

Combinatorics 2026-04-08 v1

Abstract

Addressing questions raised in recent papers, we study the rr-distance graph Hr(n)H_r(n) on the Boolean cube {0,1}n\{0,1\}^n, where two vertices are adjacent if their Hamming distance is exactly rr. For fixed integers s2s \ge 2 and even r2r \ge 2, we determine the asymptotic order of the ss-independence number αs(Hr(n))\alpha_s(H_r(n)), showing that αs(Hr(n))=Θ(2nnr/2). \alpha_s\left(H_r(n)\right)=\Theta\left(\frac{2^n}{n^{r/2}}\right). The upper bound is derived via a reduction to extremal problems for sunflower-free set systems, while the lower bound is obtained using algebraic constructions based on BCH codes and constant-weight codes.

Keywords

Cite

@article{arxiv.2604.05607,
  title  = {Forbidding Exactly One Hamming Distance},
  author = {József Balogh and Ce Chen and Bowen Li},
  journal= {arXiv preprint arXiv:2604.05607},
  year   = {2026}
}

Comments

10 pages

R2 v1 2026-07-01T11:56:58.418Z