Miklos Schweitzer 1950_3
Source: first round of 1950
October 2, 2008
combinatorics proposedcombinatorics
Problem Statement
Let be a system of n^2 \plus{} 1 closed intervals of the real line. Show that has either a subsystem consisting of n \plus{} 1 elements which are monotonically ordered with respect to inclusion or a subsystem consisting of n \plus{} 1 elements none of which contains another element of the subsystem.