Title
A degree version of the Hilton–Milner theorem ☆
Abstract
An intersecting family of sets is trivial if all of its members share a common element. Hilton and Milner proved a strong stability result for the celebrated Erdős–Ko–Rado theorem: when n>2k, every non-trivial intersecting family of k-subsets of [n] has at most (n−1k−1)−(n−k−1k−1)+1 members. One extremal family HMn,k consists of a k-set S and all k-subsets of [n] containing a fixed element x∉S and at least one element of S. We prove a degree version of the Hilton–Milner theorem: if n=Ω(k2) and F is a non-trivial intersecting family of k-subsets of [n], then δ(F)≤δ(HMn.k), where δ(F) denotes the minimum (vertex) degree of F. Our proof uses several fundamental results in extremal set theory, the concept of kernels, and a new variant of the Erdős–Ko–Rado theorem.
Year
DOI
Venue
2018
10.1016/j.jcta.2017.11.019
Journal of Combinatorial Theory, Series A
Keywords
Field
DocType
Intersecting families,Hilton–Milner theorem,Erdős–Ko–Rado theorem
Discrete mathematics,Set theory,Family of sets,Combinatorics,Erdős–Ko–Rado theorem,Vertex (geometry),Mathematics
Journal
Volume
ISSN
Citations 
155
0097-3165
3
PageRank 
References 
Authors
0.49
7
4
Name
Order
Citations
PageRank
Peter Frankl1578126.03
Jie Han2318.16
Hao Huang3102.12
Yi Zhao4406.92