Two extremal problems on intersecting families
Combinatorics
2018-05-01 v1
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 , they must satisfy ? We give an affirmative answer for , 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 , the maximum diversity of an intersecting family is equal to . We are able to find a construction beating the conjectured bound for slightly larger than , which also disproves a conjecture of Kupavskii.
Cite
@article{arxiv.1804.11269,
title = {Two extremal problems on intersecting families},
author = {Hao Huang},
journal= {arXiv preprint arXiv:1804.11269},
year = {2018}
}