MathDB
Set

Source: Chinese TST 2009 4th P3

April 5, 2009
combinatorics proposedcombinatorics

Problem Statement

Let X X be a set containing 2k 2k elements, F F is a set of subsets of X X consisting of certain k k elements such that any one subset of X X consisting of k \minus{} 1 elements is exactly contained in an element of F. F. Show that k \plus{} 1 is a prime number.
Back to ProblemsView on AoPS