IMO Shortlist 2012, Combinatorics 3
Source: IMO Shortlist 2012, Combinatorics 3
July 29, 2013
combinatoricsmatrixExtremal combinatoricsIMO Shortlist
Problem Statement
In a square table some cells are white and the remaining ones are red. Let be the number of triples of cells, the first two in the same row and the last two in the same column, with white and red. Find the maximum value can attain.Proposed by Merlijn Staps, The Netherlands