{ "id": "1806.02838", "version": "v1", "published": "2018-06-07T18:00:03.000Z", "updated": "2018-06-07T18:00:03.000Z", "title": "On Turán exponents of bipartite graphs", "authors": [ "Tao Jiang", "Jie Ma", "Liana Yepremyan" ], "categories": [ "math.CO" ], "abstract": "A long-standing conjecture of Erd\\H{o}s and Simonovits asserts that for every rational number $r\\in (1,2)$ there exists a bipartite graph $H$ such that $\\ex(n,H)=\\Theta(n^r)$. So far this conjecture is known to be true only for rationals of form $1+1/k$ and $2-1/k$, for integers $k\\geq 2$. In this paper we add a new form of rationals for which the conjecture is true; $2-2/(2k+1)$, for $k\\geq 2$. This in its turn also gives an affirmative answer to a question of Pinchasi and Sharir on cube-like graphs. Recently, a version of Erd\\H{o}s and Simonovits's conjecture where one replaces a single graph by a family, was confirmed by Bukh and Conlon. They proposed a construction of bipartite graphs which should satisfy Erd\\H{o}s and Simonovits's conjecture. Our result can also be viewed as a first step towards verifying Bukh and Conlon's conjecture. We also prove the an upper bound on the Tur\\'an's number of $\\theta$-graphs in an asymmetric setting and employ this result to obtain yet another new rational exponent for Tur\\'an exponents; $r=7/5$.", "revisions": [ { "version": "v1", "updated": "2018-06-07T18:00:03.000Z" } ], "analyses": { "keywords": [ "bipartite graph", "turán exponents", "simonovitss conjecture", "simonovits asserts", "turan exponents" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }