{ "id": "2309.00757", "version": "v1", "published": "2023-09-01T23:07:39.000Z", "updated": "2023-09-01T23:07:39.000Z", "title": "A Note on Hamiltonian-Intersecting Families of Graphs", "authors": [ "Imre Leader", "Žarko Ranđelović", "Ta Sheng Tan" ], "comment": "5 pages", "categories": [ "math.CO" ], "abstract": "How many graphs on an $n$-point set can we find such that any two have connected intersection? Berger, Berkowitz, Devlin, Doppelt, Durham, Murthy and Vemuri showed that the maximum is exactly $1/2^{n-1}$ of all graphs. Our aim in this short note is to give a 'directed' version of this result; we show that a family of oriented graphs such that any two have strongly-connected intersection has size at most $1/3^n$ of all oriented graphs. We also show that a family of graphs such that any two have Hamiltonian intersection has size at most $1/2^n$ of all graphs, verifying a conjecture of the above authors.", "revisions": [ { "version": "v1", "updated": "2023-09-01T23:07:39.000Z" } ], "analyses": { "subjects": [ "05C35" ], "keywords": [ "hamiltonian-intersecting families", "oriented graphs", "point set", "short note", "hamiltonian intersection" ], "note": { "typesetting": "TeX", "pages": 5, "language": "en", "license": "arXiv", "status": "editable" } } }