The Complexity of the Four Colour Theorem

  title={The Complexity of the Four Colour Theorem},
  author={Cristian S. Calude and Elena Calude},
The four colour theorem states that the vertices of every planar graph can be coloured with at most four colours so that no two adjacent vertices receive the same colour. This theorem is famous for many reasons, including the fact that its original 1977 proof includes a non-trivial computer verification. Recently, a formal proof of the theorem was obtained with the equational logic program Coq [14]. In this paper we describe an implementation of the computational method introduced in [7, 5] to… CONTINUE READING


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