English

$s$-almost cross-$t$-intersecting families for vector spaces

Combinatorics 2026-02-13 v1

Abstract

Let VV be an nn-dimensional vector space over the finite field Fq\mathbb{F} _{q} , and [Vk]{V\brack k} denote the family of all kk-dimensional subspaces of VV. The families F,G[Vk]\mathcal{F},\mathcal{G}\subseteq {V\brack k} are said to be cross-tt-intersecting if dim(FG)t\dim(F\cap G)\ge t for all FF,GGF\in \mathcal{F}, G\in \mathcal{G}. Two families F\mathcal{F} and G\mathcal{G} are called ss-almost cross-tt-intersecting if each member of F\mathcal{F} (resp. G\mathcal{G}) is tt-disjoint with at most ss members of G\mathcal{G} (resp. F\mathcal{F}). In this paper, we discribe the structure of ss-almost cross-tt-intersecting families with maximum product of their sizes. In addition, we prove a stability result.

Keywords

Cite

@article{arxiv.2602.11532,
  title  = {$s$-almost cross-$t$-intersecting families for vector spaces},
  author = {Dehai Liu and Jinhua Wang and Tian Yao},
  journal= {arXiv preprint arXiv:2602.11532},
  year   = {2026}
}
R2 v1 2026-07-01T10:32:57.886Z