{ "id": "1108.5254", "version": "v3", "published": "2011-08-26T08:14:56.000Z", "updated": "2012-06-03T10:50:56.000Z", "title": "Turán numbers for $K_{s,t}$-free graphs: topological obstructions and algebraic constructions", "authors": [ "Pavle Blagojević", "Boris Bukh", "Roman Karasev" ], "comment": "Fixed a small mistake in the application of Proposition 1", "journal": "Israel Journal of Mathematics 197:1 (2013), 199-214", "doi": "10.1007/s11856-012-0184-z", "categories": [ "math.CO", "math.AG", "math.AT" ], "abstract": "We show that every hypersurface in $\\R^s\\times \\R^s$ contains a large grid, i.e., the set of the form $S\\times T$, with $S,T\\subset \\R^s$. We use this to deduce that the known constructions of extremal $K_{2,2}$-free and $K_{3,3}$-free graphs cannot be generalized to a similar construction of $K_{s,s}$-free graphs for any $s\\geq 4$. We also give new constructions of extremal $K_{s,t}$-free graphs for large $t$.", "revisions": [ { "version": "v3", "updated": "2012-06-03T10:50:56.000Z" } ], "analyses": { "keywords": [ "free graphs", "turán numbers", "algebraic constructions", "topological obstructions", "large grid" ], "tags": [ "journal article" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2011arXiv1108.5254B" } } }