Notices of the American Mathematical Society
Hacker News
February 21, 2026
AI-Generated Deep Dive Summary
The Four-Color Theorem, first posed in 1852 by Francis Guthrie, asks whether any map can be colored with just four colors such that no two adjacent regions share the same color. This problem remained unsolved for over a century until Kenneth Appel and Wolfgang Haken provided a definitive proof in 1976, marking a major milestone in mathematics. The theorem’s history is rich with contributions from key figures like Augustus De Morgan, who popularized the problem, and Francis Guthrie, the student who originally posed it to his professor. Their correspondence highlights how the problem evolved from a simple query about map coloring to a groundbreaking mathematical achievement.
De Morgan, a prominent mathematician and logician, played a crucial role in spreading awareness of the four-color problem. In 1852, he shared Guthrie’s question with his colleague Sir William Rowan Hamilton, sparking further interest. De Morgan mistakenly believed that if four regions were mutually adjacent, one must be enclosed by the others—a notion later proven false. Despite this error, De Morgan’s efforts helped establish the problem as a significant challenge in mathematics. The theorem gained wider recognition when it was published in *The Athenaeum* in 1854, under the pseudonym “F. G.”, likely Francis Guthrie.
The four-color problem has often been mistakenly attributed to German mathematician August Möbius, who posed a similar but distinct challenge about dividing land among five sons. While this misunderstanding adds complexity to the theorem’s history,
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Originally published on Hacker News on 2/21/2026