{ "id": "1605.07791", "version": "v1", "published": "2016-05-25T09:18:56.000Z", "updated": "2016-05-25T09:18:56.000Z", "title": "A proof of Mader's conjecture on large clique subdivisions in $C_4$-free graphs", "authors": [ "Hong Liu", "Richard Montgomery" ], "comment": "25 pages, 1 figure", "categories": [ "math.CO" ], "abstract": "Given any integers $s,t\\geq 2$, we show there exists some $c=c(s,t)>0$ such that any $K_{s,t}$-free graph with average degree $d$ contains a subdivision of a clique with at least $cd^{\\frac{1}{2}\\frac{s}{s-1}}$ vertices. In particular, when $s=2$ this resolves in a strong sense the conjecture of Mader in 1999 that every $C_4$-free graph has a subdivision of a clique with order linear in the average degree of the original graph. In general, the widely conjectured asymptotic behaviour of the extremal density of $K_{s,t}$-free graphs suggests our result is tight up to the constant $c(s,t)$.", "revisions": [ { "version": "v1", "updated": "2016-05-25T09:18:56.000Z" } ], "analyses": { "keywords": [ "free graph", "large clique subdivisions", "maders conjecture", "average degree", "extremal density" ], "note": { "typesetting": "TeX", "pages": 25, "language": "en", "license": "arXiv", "status": "editable" } } }