We construct an infinite family of intriguing sets that are not tight in the Grassmann Graph of planes of PG(n,q), n≥5 odd, and show that the members of the family are the smallest possible examples if n≥9 or q≥25.
@article{arxiv.1809.02644,
title = {Intriguing sets in distance regular graphs},
author = {Stefaan De Winter and Klaus Metsch},
journal= {arXiv preprint arXiv:1809.02644},
year = {2018}
}