The Hadwiger–Nelson problem
What is the minimum number of colours needed to colour the plane in such a way that any two points that are at distance 1 from each other always have different colours? This is known as the Hadwiger–…
What is the minimum number of colours needed to colour the plane in such a way that any two points that are at distance 1 from each other always have different colours? This is known as the Hadwiger–…