Forbidden formations in 0-1 matrices

Abstract

Keszegh (2009) proved that the extremal function $ex(n,P)$ of any forbidden light $2$-dimensional 0-1 matrix $P$ is at most quasilinear in $n$, using a reduction to generalized Davenport-Schinzel sequences. We extend this result to multidimensional matrices by proving that any light $d$-dimensional 0-1 matrix $P$ has extremal function $ex(n,P,d)=O(n^{d-1}{2}^{\alpha (n{)}^t})$ for some constant $t$ that depends on $P$. To prove this result, we introduce a new family of patterns called $(P,s)$-formations, which are a generalization of $(r,s)$-formations, and we prove upper bounds on their extremal functions. In many cases, including permutation matrices $P$ with at least two ones, we are able to show that our $(P,s)$-formation upper bounds are tight.

arXiv comment11 pages