*********************************** * Princeton Discrete Math Seminar * *********************************** Speaker: Oliver Janzer (ETH Zurich) Thursday 18th November, 3:00 via Zoom. Zoom link https://princeton.zoom.us/j/93006186024, password will be mailed to the seminar list. Title: Disproof of a conjecture of Erdős and Simonovits on the Turán number of graphs with minimum degree 3 In 1981, Erdős and Simonovits conjectured that for any bipartite graph H we have ex(n,H)=O(n^{3/2}) if and only if H is 2-degenerate. Later, Erdős offered 250 dollars for a proof and 500 dollars for a counterexample. We disprove the conjecture by finding, for any epsilon>0, a 3-regular bipartite graph H with ex(n,H)=O(n^{4/3+epsilon}). ---------------------------------- Next week: Thanksgiving break. Week after: Samuel Mohr Anyone wishing to be added to or removed from this mailing list should contact Paul Seymour (pds@math.princeton.edu)