Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
11017677 | European Journal of Combinatorics | 2019 | 9 Pages |
Abstract
In this short note, we address two problems in extremal set theory regarding intersecting families. The first problem is a question posed by Kupavskii: is it true that given two disjoint cross-intersecting families A,Bâ[n]k, they must satisfy min{|A|,|B|}â¤12nâ1kâ1? We give an affirmative answer for nâ¥2k2, and construct families showing that this range is essentially the best one could hope for, up to a constant factor. The second problem is a conjecture of Frankl. It states that for nâ¥3k, the maximum diversity of an intersecting family Fâ[n]k is equal to nâ3kâ2. We are able to find a construction beating the conjectured bound for n slightly larger than 3k, which also disproves a conjecture of Kupavskii.
Related Topics
Physical Sciences and Engineering
Mathematics
Discrete Mathematics and Combinatorics
Authors
Hao Huang,