We investigate the conditions under which an association scheme exists on the set of lines of a regular near hexagon with quads of order \((s, t_2)\) passing through every two points at distance \(2\). Specifically, we determine all regular near hexagons admitting such an association scheme when \(s \geq t_2\), while the case \(t^2 > s\) remains open.
Citation
Bart De Bruyn. Association Schemes on the Sets of Lines of Regular Near Hexagons[J], Ars Combinatoria, Volume 115. 283-292. .