Minimum number of sets!
Source: Greek MO 2013 - P3
May 12, 2013
combinatorics proposedcombinatorics
Problem Statement
We define the sets such that for all . With the elements of these sets we create new sets by the following procedure: in the first step we choose some of the sets and we remove from each of them the same number of elements. These elements that we removed are the elements of . In the second step we repeat the same procedure in the sets that came of the implementation of the first step and so we define . We continue similarly until there are no more elements in , thus defining the sets . Find the minimum value of .