Log concavity and concentration of Lipschitz functions on the Boolean hypercube
Abstract
It is well-known that measures whose density is the form where is a uniformly convex potential on attain strong concentration properties. In search of a notion of log-concavity on the discrete hypercube, we consider measures on whose multi-linear extension satisfies , for , which we refer to as -semi-log-concave. We prove that these measures satisfy a nontrivial concentration bound, namely, any Hamming Lipchitz test function satisfies for . As a corollary, we prove a concentration bound for measures which exhibit the so-called Rayleigh property. Namely, we show that for measures such that under any external field (or exponential tilt), the correlation between any two coordinates is non-positive, Hamming-Lipschitz functions admit nontrivial concentration.
Cite
@article{arxiv.2007.13108,
title = {Log concavity and concentration of Lipschitz functions on the Boolean hypercube},
author = {Ronen Eldan and Omer Shamir},
journal= {arXiv preprint arXiv:2007.13108},
year = {2020}
}
Comments
Preliminary version