{ "id": "2104.13089", "version": "v1", "published": "2021-04-27T10:19:58.000Z", "updated": "2021-04-27T10:19:58.000Z", "title": "Large non-trivial $t$-intersecting families for signed sets", "authors": [ "Tian Yao", "Benjian Lv", "Kaishun Wang" ], "categories": [ "math.CO" ], "abstract": "For positive integers $n,r,k$ with $n\\ge r$ and $k\\ge2$, a set $\\{(x_1,y_1),(x_2,y_2),\\dots,(x_r,y_r)\\}$ is called a $k$-signed $r$-set on $[n]$ if $x_1,\\dots,x_r$ are distinct elements of $[n]$ and $y_1\\dots,y_r\\in[k]$. We say a $t$-intersecting family consisting of $k$-signed $r$-sets on $[n]$ is trivial if each member of this family contains a fixed $k$-signed $t$-set. In this paper, we determine the structure of large maximal non-trivial $t$-intersecting families. In particular, we characterize the non-trivial $t$-intersecting families with maximum size for $t\\ge2$, extending a Hilton-Milner-type result for signed sets given by Borg.", "revisions": [ { "version": "v1", "updated": "2021-04-27T10:19:58.000Z" } ], "analyses": { "subjects": [ "05D05" ], "keywords": [ "intersecting family", "signed sets", "large non-trivial", "large maximal non-trivial", "distinct elements" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }