About ternary families of an n-set
Source: Brazil Mathematical Olympiad 1995
March 17, 2006
ceiling functionfloor functioncombinatorics proposedcombinatorics
Problem Statement
has elements. is a family of subsets of each with three elements, such that any two of the subsets have at most one element in common. Show that there is a subset of with at least members which does not contain any members of .