Problems / combinatorics
combinatorics / Random graphs, analysis of Boolean functions
The Friedgut-Kalai sharp-threshold conjecture: threshold width O(1/log^2 n) for monotone graph properties
Theorem 1.1: for every n≥2, nontrivial increasing vertex-symmetric graph property and 0<ε<1/2, p1−ε−pε≤219log(1/(2ε))/(logn)2. It follows from Theorem 1.2, Varp(f)≤217Ip(f)/(logn)2 for every vertex-symmetric Boolean f and every 0<p<1, without monotonicity, which removes the (loglogn)2 loss of Kelman-Kindler-Lifshitz-Minzer-Safra at p=1/2. The order is optimal for fixed ε (clique example). Not shown: the best constant, or where thresholds lie (a different question).