A 910-block explicit construction guaranteeing a triple intersection with every $6$-subset of $[60]$
Combinatorics
2026-02-05 v1
Abstract
We present a simple explicit family of -subsets of such that every -subset intersects at least one block in at least three elements, i.e.\ . Equivalently, is a covering (dominating set) of the Johnson graph with covering radius in the Johnson metric. The construction is purely combinatorial, based on a fixed split of into two halves, a pairing of each half, and a pigeonhole argument. We also record a crude counting lower bound and a straightforward generalization to (with even).
Cite
@article{arxiv.2602.04867,
title = {A 910-block explicit construction guaranteeing a triple intersection with every $6$-subset of $[60]$},
author = {Paulo Henrique Cunha Gomes},
journal= {arXiv preprint arXiv:2602.04867},
year = {2026}
}