{ "id": "2105.07979", "version": "v2", "published": "2021-05-17T16:02:55.000Z", "updated": "2021-05-20T15:07:43.000Z", "title": "Designs, permutations, and transitive groups", "authors": [ "Minjia Shi", "XiaoXiao Li", "Patrick Solé" ], "comment": "12 pages. arXiv admin note: text overlap with arXiv:2102.08276", "categories": [ "math.CO", "cs.DM" ], "abstract": "A notion of $t$-designs in the symmetric group on $n$ letters was introduced by Godsil in 1988. In particular $t$-transitive sets of permutations form a $t$-design. We derive special lower bounds for $t=1$ and $t=2$ by a power moment method. For general $n,t$ we give a %linear programming lower bound . For $n\\ge 4$ and $t=2,$ this bound is strong enough to show a lower bound on the size of such $t$-designs of $n(n-1)\\dots (n-t+1),$ which is best possible when sharply $t$-transitive sets of permutations exist. This shows, in particular, that tight $2$-designs do not exist.", "revisions": [ { "version": "v2", "updated": "2021-05-20T15:07:43.000Z" } ], "analyses": { "subjects": [ "05E35", "05E24" ], "keywords": [ "transitive groups", "power moment method", "derive special lower bounds", "transitive sets", "programming lower bound" ], "note": { "typesetting": "TeX", "pages": 12, "language": "en", "license": "arXiv", "status": "editable" } } }