Pei Wu, Institute for Advanced Study

Abstract

In the talk, we discuss the probability of Boolean functions with small max influence to become constant under random restrictions. Let f be a Boolean function such that the variance of f is $Omega(1)$ and all its individual influences are bounded by $tau$. We show that when restricting all but a $tilde{Omega}((log1/tau)^{-1})$ fraction of the coordinates, the restricted function remains nonconstant with overwhelming probability. This bound is essentially optimal, as witnessed by the tribes function $AND_{n/Clog n} circ OR_{Clog n}$.

We extend it to an anti-concentration result, showing that the restricted function has nontrivial variance with probability 1-o(1). This gives a sharp version of the ``it ain't over till it's over'' theorem due to Mossel, O'Donnell, and Oleszkiewicz.

Joint work with Avi Wigderson and Ronen Eldan.