Title
2-Bases of Quadruples
Abstract
Let $\cal{B}(n, \leq 4)$ denote the subsets of $[n]:=\{ 1, 2, \dots, n\}$ of at most 4 elements. Suppose that $\cal{F}$ is a set system with the property that every member of $\cal{B}$ can be written as a union of (at most) two members of $\cal{F}$. (Such an $\cal{F}$ is called a 2-base of $\cal{B}$.) Here we answer a question of Erdös proving that \[|\FF|\geq 1+n+\binom{n}{2}- \Bigl\lfloor \frac{4}{3}n\Bigr\rfloor\], and this bound is best possible for $n\geq 8$.
Year
DOI
Venue
2006
10.1017/S0963548305007248
Combinatorics, Probability & Computing
Keywords
Field
DocType
set system
Discrete mathematics,Combinatorics,Mathematics
Journal
Volume
Issue
ISSN
15
1-2
0963-5483
Citations 
PageRank 
References 
4
0.69
2
Authors
2
Name
Order
Citations
PageRank
Zoltán Füredi11237233.60
Gyula O. H. Katona226466.44