Erdos-Ko-Rado-type theorems for colored sets

Abstract

An Erdos-Ko-Rado-type theorem was established by Bollobás and Leader for q-signed sets and by Ku and Leader for partial permutations. In this paper, we establish an LYM-type inequality for partial permutations, and prove Ku and Leader's conjecture on maximal k-uniform intersecting families of partial permutations. Similar results on general colored sets are presented.