{ "id": "1806.00825", "version": "v1", "published": "2018-06-03T16:27:11.000Z", "updated": "2018-06-03T16:27:11.000Z", "title": "Short rainbow cycles in sparse graphs", "authors": [ "Matt DeVos", "Sebastián González Hermosillo de la Maza", "Krystal Guo", "Daryl Funk", "Tony Huynh", "Bojan Mohar", "Amanda Montejano" ], "comment": "6 pages, 2 figures", "categories": [ "math.CO", "cs.DM" ], "abstract": "Let $G$ be a simple $n$-vertex graph and $c$ be a colouring of $E(G)$ with $n$ colours, where each colour class has size at least $2$. We prove that $G$ contains a rainbow cycle of length at most $\\lceil \\frac{n}{2} \\rceil$, which is best possible. Our result settles a special case of a strengthening of the Caccetta-H\\\"aggkvist conjecture, due to Aharoni. We also show that the matroid generalization of our main result also holds for cographic matroids, but fails for binary matroids.", "revisions": [ { "version": "v1", "updated": "2018-06-03T16:27:11.000Z" } ], "analyses": { "subjects": [ "05C15", "05C20", "05C38" ], "keywords": [ "short rainbow cycles", "sparse graphs", "colour class", "matroid generalization", "main result" ], "note": { "typesetting": "TeX", "pages": 6, "language": "en", "license": "arXiv", "status": "editable" } } }