{ "id": "1301.4764", "version": "v1", "published": "2013-01-21T06:36:46.000Z", "updated": "2013-01-21T06:36:46.000Z", "title": "The 3-way intersection problem for S(2, 4, v) designs", "authors": [ "Saeedeh Rashidi", "Nasrin Soltankhah" ], "comment": "accepted in Utilitas mathematics", "categories": [ "math.CO" ], "abstract": "In this paper the 3-way intersection problem for $S(2,4,v)$ designs is investigated. Let $b_{v}=\\frac {v(v-1)}{12}$ and $I_{3}[v]=\\{0,1,...,b_{v}\\}\\setminus\\{b_{v}-7,b_{v}-6,b_{v}-5,b_{v}-4,b_{v}-3,b_{v}-2,b_{v}-1\\}$. Let $J_{3}[v]=\\{k|$ there exist three $S(2,4,v)$ designs with $k$ same common blocks$\\}$. We show that $J_{3}[v]\\subseteq I_{3}[v]$ for any positive integer $v\\equiv1, 4\\ (\\rm mod \\ 12)$ and $J_{3}[v]=I_{3}[v]$, for $ v\\geq49$ and $v=13 $. We find $J_{3}[16]$ completely. Also we determine some values of $J_{3}[v]$ for $\\ v=25,28,37$ and 40.", "revisions": [ { "version": "v1", "updated": "2013-01-21T06:36:46.000Z" } ], "analyses": { "keywords": [ "intersection problem", "common blocks", "positive integer" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1301.4764R" } } }