http://theconversation.com/putting-maths-on-the-map-with-the-four-colour-theorem-16988

In this article it explains to us the real ways that the Four Color Theorem came to be. In 1976, Kenneth Appel and Wolfgang Haken finally succeeded in approving the color theorem but were unable to prove to others how the Four Color Theorem works without suggesting to draw an infinite number of maps to prove it. The truth of the matter was that proving the Four Color Theorem would only be possible with the help of computers. They used the *reductio ad absurdum* (reduction to absurdity) method. This states that “If we want to prove that something is true, we instead assume that it is false and show that the rest of math goes bad. That is, by assuming falsity, we encounter contradictions to already known truths.” So, Appel and Haken used this idea along with a computer program to work on any map, assuming that there might’ve been a map out there that needed more than four colors. After the computer proved that no map needed more than four colors to complete the four color theorem became the first major mathematical theorem to be proved using a computer. Who knows if this could’ve ever been truly proven without the help of technology?