A lower bound for essential covers of the cube

Abstract

Essential covers were introduced by Linial and Radhakrishnan as a model that captures two complementary properties: (1) all variables must be included and (2) no element is redundant. In their seminal paper, they proved that every essential cover of the $n$-dimensional hypercube must be of size at least $\Omega(n^{0.5})$. Later on, this notion found several applications in complexity theory. We improve the lower bound to $\Omega(n^{0.52})$, and describe two applications.