English

Some locally Kneser graphs

Combinatorics 2023-12-06 v1

Abstract

The Kneser graph K(n,d)K(n,d) is the graph on the dd-subsets of an nn-set, adjacent when disjoint. Clearly, K(n+d,d)K(n+d,d) is locally K(n,d)K(n,d). Hall showed for n3d+1n \ge 3d+1 that there are no further examples. Here we give other examples of locally K(n,d)K(n,d) graphs for n=3dn = 3d, and some further sporadic examples. It follows that Hall's bound is best possible.

Keywords

Cite

@article{arxiv.2312.02964,
  title  = {Some locally Kneser graphs},
  author = {A. E. Brouwer},
  journal= {arXiv preprint arXiv:2312.02964},
  year   = {2023}
}
R2 v1 2026-06-28T13:41:58.842Z