Two-part set systems
Combinatorics
2016-08-14 v1
Abstract
The two part Sperner theorem of Katona and Kleitman states that if is an -element set with partition , and is a family of subsets of such that no two sets satisfy (or ) and for some , then . We consider variations of this problem by replacing the Sperner property with the intersection property and considering families that satisfiy various combinations of these properties on one or both parts , . Along the way, we prove the following new result which may be of independent interest: let be families of subsets of an -element set such that and are both intersecting and cross-Sperner, meaning that if and , then and . Then and there are exponentially many examples showing that this bound is tight.
Keywords
Cite
@article{arxiv.1110.0099,
title = {Two-part set systems},
author = {Dániel Gerbner and Péter L. Erdős and Nathan Lemons and Dhruv Mubayi and Cory Palmer and Balázs Patkós},
journal= {arXiv preprint arXiv:1110.0099},
year = {2016}
}