Problem #PRU-60365

Problemas Matemáticas Discretas Combinatoria Geometría en papel cuadrado Problemas de pintura Métodos Principio del casillero Principio del casillero (otro)

Problem

An endless board is painted in three colours (each cell is painted in one of the colours). Prove that there are four cells of the same colour, located at the vertices of the rectangle with sides parallel to the side of one cell.