English

Vector sum-intersection theorems

Combinatorics 2023-05-03 v1

Abstract

We introduce the following generalization of set intersection via characteristic vectors: for n,q,s,t1n,q,s, t \ge 1 a family F{0,1,,q}n\mathcal{F}\subseteq \{0,1,\dots,q\}^n of vectors is said to be \emph{ss-sum tt-intersecting} if for any distinct x,yF\mathbf{x},\mathbf{y}\in \mathcal{F} there exist at least tt coordinates, where the entries of x\mathbf{x} and y\mathbf{y} sum up to at least ss, i.e.\ {i:xi+yis}t|\{i:x_i+y_i\ge s\}|\ge t. The original set intersection corresponds to the case q=1,s=2q=1,s=2. We address analogs of several variants of classical results in this setting: the Erd\H{o}s--Ko--Rado theorem and the theorem of Bollob\'as on intersecting set pairs.

Keywords

Cite

@article{arxiv.2305.01328,
  title  = {Vector sum-intersection theorems},
  author = {Balázs Patkós and Zsolt Tuza and Máté Vizer},
  journal= {arXiv preprint arXiv:2305.01328},
  year   = {2023}
}