The four colour theorem: why every map needs only four crayons.
A schoolboy's question in 1852, a century of failed proofs, and the first major theorem settled by a computer that no human could fully check by hand.
Varchas KoushikFounder · Storyteller & Learning Experience Designer
The colours on maps got me thinking about why they are shown that way, and that led me to the four colour theorem — the subject of story #52.
The four colour theorem was the first important theorem to be established by a computer-assisted proof, one that is extremely difficult for a person to verify by hand.
The theorem says that every map in a plane can be coloured using four colours in a way that prevents regions sharing a boundary (other than a single point) from having the same colour.
In honour of Francis Guthrie, who first proposed it in 1852, the problem is also known as Guthrie's problem. The conjecture was communicated to De Morgan and from there to the wider community; Cayley published the first paper on it in 1878.
Despite the motivation from colouring political maps, the theorem is not of particular interest to cartographers. And although some sceptics remain — thanks to a number of fallacious proofs along the way — the theorem has gained widespread acceptance.
Also: 52nd story — one story a week for a year. I didn't expect to continue this series for so long, but I can't say no to math, right?
First published on LinkedIn as Math Storytelling #52
Written by
Varchas Koushik
Founder · Storyteller & Learning Experience Designer
Founder of All Things Classroom. 10,000+ hours facilitating sessions with students across age groups and geographies; writes about game-based learning, story-driven teaching and what's possible when a lesson is designed like an experience instead of a script.
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