{ "id": "2410.19422", "version": "v1", "published": "2024-10-25T09:27:38.000Z", "updated": "2024-10-25T09:27:38.000Z", "title": "Flag-transitive point-primitive quasi-symmetric $2$-designs with block intersection numbers $0$ and $y\\leq10$", "authors": [ "Jianbing Lu", "Yu Zhuang" ], "categories": [ "math.CO" ], "abstract": "In this paper, we show that for a non-trivial quasi-symmetric $2$-design $\\mathcal{D}$ with two block intersection numbers $x=0$ and $2\\leq y\\leq10$, if $G\\leq \\mathrm{Aut}(\\mathcal{D})$ is flag-transitive and point-primitive, then $G$ is either of affine type or almost simple type. Moreover, we prove that the socle of $G$ cannot be an alternating group. If the socle of $G$ is a sporadic group, then $\\mathcal{D}$ and $G$ must be one of the following: $\\mathcal{D}$ is a $2$-$(12,6,5)$ design with block intersection numbers $0,3$ and $G=\\mathrm{M}_{11}$, or $\\mathcal{D}$ is a $2$-$(22,6,5)$ design with block intersection numbers $0,2$ and $G=\\mathrm{M}_{22}$ or $\\mathrm{M}_{22}:2$.", "revisions": [ { "version": "v1", "updated": "2024-10-25T09:27:38.000Z" } ], "analyses": { "keywords": [ "block intersection numbers", "flag-transitive point-primitive quasi-symmetric", "sporadic group", "non-trivial quasi-symmetric", "affine type" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }