MathDB
Biggest number of sets

Source: Serbia TST 2009

April 17, 2009
floor functioncombinatorics unsolvedcombinatorics

Problem Statement

Find the largest natural number n n for which there exist different sets S1,S2,,Sn S_1,S_2,\ldots,S_n such that: 1 1^\circ SiSj2004 |S_i\cup S_j|\leq 2004 for each two 1i,jn 1\leq i,j\le n and 2 2^\circ S_i\cup S_j\cup S_k\equal{}\{1,2,\ldots,2008\} for each three integers 1i<j<kn 1\le i<j<k\le n.