One taken from each of any n − 1 of the subsets
Source: IMO Shortlist 1995, N7
August 10, 2008
combinatoricspartitionAdditive combinatoricsAdditive Number TheoryIMO Shortlist
Problem Statement
Does there exist an integer which satisfies the following condition? The set of positive integers can be partitioned into nonempty subsets, such that an arbitrary sum of n \minus{} 1 integers, one taken from each of any n \minus{} 1 of the subsets, lies in the remaining subset.