Four-Color Theorem Is Still a Math Favorite

In 1852, the mathematician Francis Guthrie was coloring in a map of English counties when he noticed that he needed only four colors. Was this always true, he wondered? The question captured the imagination of hobbyists and professionals alike — and in 1976, the mathematicians Kenneth Appel and Wolfgang Haken proved it, rather controversially using computers. Recently, mathematicians have revisited the four-color theorem and found a more efficient way to color maps with just four colors. On this episode of The Quanta Podcast, host Samir Patel speaks with writer Greg Barber about the “four-color disease,” its history of false starts and dashed hopes, and what modern mathematicians have learned about graphs by revisiting this famous problem. This topic was covered in a recent story for Quanta Magazine.   Each week on The Quanta Podcast, Quanta Magazine editor-in-chief Samir Patel and Senior Editor Hannah Waters speak with the people behind the award-winning publication to navigate through some of the most important and mind-expanding questions in science and math.