- Futurama episode 'The Prisoner of Benda' features a mind-swapping machine that can only be used once per pair of bodies.
- Writer Ken Keeler, who holds a PhD in mathematics, formulated an original proof to solve the resulting body-swapping chaos.
- Keeler's proof demonstrates that only two additional characters are needed to untangle any number of swapped minds.
- The solution involves systematically swapping misplaced minds with the two extra characters in a specific sequence.
- The proof was later published and refined by mathematicians Ron Evans, Lihua Huang, and Tuan Nguyen in 2014.
- The episode successfully presents a genuine mathematical problem and its solution without sacrificing entertainment value.