2 points with same colore at distance \sqrt5 , 4 colours in 2x4
Source: Portugal OPM 2002 p3
May 19, 2024
combinatorial geometrygeometryColoringcombinatorics
Problem Statement
Daniel painted a rectangular painting measuring meters by meters with four colors. Knowing that he used more than two colors to paint the four corners of the painting, prove that he painted of the same color two points that are at least meters