{ "id": "1409.0972", "version": "v1", "published": "2014-09-03T07:14:37.000Z", "updated": "2014-09-03T07:14:37.000Z", "title": "Cycles in Oriented 3-graphs", "authors": [ "Imre Leader", "Ta Sheng Tan" ], "comment": "12 pages", "categories": [ "math.CO" ], "abstract": "An oriented 3-graph consists of a family of triples (3-sets), each of which is given one of its two possible cyclic orientations. A cycle in an oriented 3-graph is a positive sum of some of the triples that gives weight zero to each 2-set. Our aim in this paper is to consider the following question: how large can the girth of an oriented 3-graph (on $n$ vertices) be? We show that there exist oriented 3-graphs whose shortest cycle has length $\\frac{n^2}{2}(1+o(1))$: this is asymptotically best possible. We also show that there exist 3-tournaments whose shortest cycle has length $\\frac{n^2}{3}(1+o(1))$, in complete contrast to the case of 2-tournaments.", "revisions": [ { "version": "v1", "updated": "2014-09-03T07:14:37.000Z" } ], "analyses": { "keywords": [ "shortest cycle", "cyclic orientations", "weight zero", "complete contrast", "positive sum" ], "note": { "typesetting": "TeX", "pages": 12, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1409.0972L" } } }