A combi with painting chess table
Source: Turkey EGMO TST 2020 #4
July 15, 2020
combinatoricscombinatorics proposed
Problem Statement
Every square of a chess table is painted in red or white. For every two columns and two rows, at least two of the intersection squares satisfies that they are in the same column or row and they are painted in the same color. Find the least value of number of columns and rows that are completely painted in one color.