The theorem was first conjectured in the mid-19th century by British mathematician Francis Guthrie, who noticed that four colours seemed sufficient to colour any map. The conjecture gained attention and sparked interest among mathematicians. The first published mention of the problem occurred in 1852.
The Four Color Theorem remained unsolved for over a century until it was finally proven by mathematicians Kenneth Appel and Wolfgang Haken in 1976. Their proof was controversial because it relied heavily on computer assistance due to the complexity of the problem. The proof essentially involved an exhaustive examination of many cases, and it was the first major theorem to be proved using a computer. While the proof is not easily verifiable by humans without computers, it is widely accepted within the mathematical community.
