English

Extensions of a Family for Sunflowers

Combinatorics 2025-04-30 v2

Abstract

This paper explores the structure of the combinatorial domain 2X2^X in relation to sunflowers. The previous study found some intrinsic properties of the ll-extension Ext(F,l)={V : V(Xl), UF UV} Ext \left( \mathcal{F}, l \right) = \left\{ V ~:~ V \in {X \choose l},~ \exists U \in \mathcal{F}~ U \subset V \right\} of a family F\mathcal{F} of mm-cardinality sets. Subsequently, it lead to the proof that such an F\mathcal{F} includes three mutually disjoint sets if it satisfies the Γ(b)\Gamma(b)-condition, that is, F[S]<bSFfor every nonempty set S,whereF[S]:={U:UF, SU}, \left| \mathcal{F}[S] \right| < b^{-|S|} |\mathcal{F}| \quad \textrm{for every nonempty set}~ S, \qquad \textrm{where} \quad \mathcal{F} [S] := \left\{ U : U \in \mathcal{F},~ S \subset U \right\}, for b=m12+ϵb= m^{\frac{1}{2}+ \epsilon} with an mm sufficiently larger than a given constant 1/ϵ1/\epsilon. It is stronger than the statement that F\mathcal{F} includes a 3-sunflower if F>bm|\mathcal{F}| > b^m, where kk-sunflower refers to a family of kk different sets with a common pair-wise intersection. Further refining the theory, we show that an F\mathcal{F} includes kk mutually disjoint sets if it satisfies the Γ(8log2mm klog2k)\Gamma \left( 8^{\sqrt{\log_2 m}} \sqrt m ~k \log_2 k \right)-condition with an mm sufficiently larger than kk.

Keywords

Cite

@article{arxiv.2301.04219,
  title  = {Extensions of a Family for Sunflowers},
  author = {Junichiro Fukuyama},
  journal= {arXiv preprint arXiv:2301.04219},
  year   = {2025}
}

Comments

32 pages. Please visit https://sites.psu.edu/sunflowerconjecture/2022/12/18/index-page/ for additional extensive information