English

Nondegenerate hyperplane covers of the hypercube

Combinatorics 2026-03-06 v2

Abstract

We consider collections of hyperplanes in Rn\mathbb{R}^n covering all vertices of the nn-dimensional hypercube {0,1}n\{0,1\}^n, which satisfy the following nondegeneracy condition: For every v{0,1}nv\in \{0,1\}^n and every i=1,,ni=1,\dots,n, we demand that there is a hyperplane HH in the collection with vHv\in H such that the variable xix_i appears with a non-zero coefficient in the hyperplane equation describing HH. We prove that every collection H\mathcal{H} of hyperplanes in Rn\mathbb{R}^n covering {0,1}n\{0,1\}^n with this nondegeneracy condition must have size Hn/2|\mathcal{H}|\ge n/2. This bound is tight up to constant factors. It generalizes a recent result concerning the intensively studied skew covers problem, which asks about the minimum possible size of a hyperplane cover of {0,1}n\{0,1\}^n in which all variables appear with non-zero coefficients in all hyperplane equations. As an application of our result, we also obtain an essentially tight bound for an old problem about collections of hyperplanes slicing all edges of the nn-dimensional hypercube, in the case where all of the hyperplanes have bounded integer coefficients.

Keywords

Cite

@article{arxiv.2507.00773,
  title  = {Nondegenerate hyperplane covers of the hypercube},
  author = {Lisa Sauermann and Zixuan Xu},
  journal= {arXiv preprint arXiv:2507.00773},
  year   = {2026}
}

Comments

v2, 6 pages, incorporated comments from referees

R2 v1 2026-07-01T03:41:37.475Z