English

Forbidden formations in 0-1 matrices

Combinatorics 2018-05-16 v1 Discrete Mathematics

Abstract

Keszegh (2009) proved that the extremal function ex(n,P)ex(n, P) of any forbidden light 22-dimensional 0-1 matrix PP is at most quasilinear in nn, using a reduction to generalized Davenport-Schinzel sequences. We extend this result to multidimensional matrices by proving that any light dd-dimensional 0-1 matrix PP has extremal function ex(n,P,d)=O(nd12α(n)t)ex(n, P,d) = O(n^{d-1}2^{\alpha(n)^{t}}) for some constant tt that depends on PP. To prove this result, we introduce a new family of patterns called (P,s)(P, s)-formations, which are a generalization of (r,s)(r, s)-formations, and we prove upper bounds on their extremal functions. In many cases, including permutation matrices PP with at least two ones, we are able to show that our (P,s)(P, s)-formation upper bounds are tight.

Keywords

Cite

@article{arxiv.1805.05328,
  title  = {Forbidden formations in 0-1 matrices},
  author = {Jesse Geneson},
  journal= {arXiv preprint arXiv:1805.05328},
  year   = {2018}
}

Comments

11 pages

R2 v1 2026-06-23T01:54:30.416Z