Essential covers of the hypercube require many hyperplanes
Lisa Sauermann, Zixuan Xu
TL;DR
This work proves a new lower bound for the size of essential covers of the $n$-dimensional hypercube by hyperplanes with full variable participation, showing any essential cover must have at least $10^{-2}\cdot n^{2/3}/(\log n)^{2/3}$ hyperplanes. The proof combines a structured coefficient-matrix decomposition with a probabilistic uncovered-vertex construction, leveraging tools such as magnitude decompositions, Bang's lemma, and Hoeffding-type concentration to force a contradiction with essential-cover minimality. The approach refines prior methods (e.g., Yehuda--Yehudayoff, Araujo--Balogh--Mattos) and yields implications for related proof-complexity lower bounds. Overall, it advances understanding of geometric covers of the hypercube and tightens the landscape of lower bounds in this domain.
Abstract
We prove a new lower bound for the almost 20 year old problem of determining the smallest possible size of an essential cover of the $n$-dimensional hypercube $\{\pm 1\}^n$, i.e. the smallest possible size of a collection of hyperplanes that forms a minimal cover of $\{\pm 1\}^n$ and such that furthermore every variable appears with a non-zero coefficient in at least one of the hyperplane equations. We show that such an essential cover must consist of at least $10^{-2}\cdot n^{2/3}/(\log n)^{2/3}$ hyperplanes, improving previous lower bounds of Linial-Radhakrishnan, of Yehuda-Yehudayoff and of Araujo-Balogh-Mattos.
