Friedgut; Dec 29 ------------------------------------------------------------ Joint Technion and University of Haifa Combinatorics Seminar ------------------------------------------------------------ The next meeting of the Combinatorics Seminar will take place on Wednesday, December 29 in *University of Haifa*. ** NOTICE THE CHANGE IN TIME. FOLLOWING REQUESTS OF SOME OF THE PARTICIPANTS, WE WILL SWITCH TO 13:10 ** ** Organizer note: Ehud will speak about a recent breakthrough in Extremal Set Theory. See also the following weblog post of Gil Kalai: <http://gilkalai.wordpress.com/2010/10/25/the-simonovits-sos-conjecture-was-proved-by-ellis-filmus-and-friedgut/> Speaker: Ehud Friedgut (Hebrew University) Time: Wednesday, December 29, 13:10 Place: Science and Education Building, room #614 (6'th floor), University of Haifa. Title: Triangle-intersecting families of graphs Abstract: How many graphs can you choose on a fixed set of n vertices such that the intersection of any two of them contains a triangle? Sos and Simonovits conjectured in 1976 that the largest such families of graphs are obtained by taking all graphs containing a fixed triangle, and that these are the only extremal constructions. This question turned out to be relatively resilient to the standard methods in extremal combinatorics, with partial progress being made in 1986 after Chung-Graham-Frankl-Shearer introduced some novel entropy arguments. Recently, with David Ellis and Yuval Filmus, we have been able to prove the conjecture, using discrete Fourier analysis and spectral methods. In this talk I'll sketch the proof. --------------------------------------------------------- Technion Math Net-2 (TECHMATH2) Editor: Michael Cwikel <techm@math.technion.ac.il> Announcement from: Raphael Yuster <raphael.yuster@gmail.com>