Puzzles

Turn CAT into DOG, one letter at a time, always landing on a real word

Change one letter at a time — never rearranging, adding or removing letters — so that every intermediate step is itself a real word, until CAT becomes DOG. What's the shortest chain?

Reveal the answer

CAT, COT, DOT, DOG — three steps. Lewis Carroll invented the game in 1877 and published puzzles under the name 'Doublets' in Vanity Fair magazine in 1879, before collecting them into a book the same year. Computer scientists later recognised it as a real-world example of a graph search problem, now usually called a 'word ladder.'

— Lewis Carroll, Doublets: A Word-Puzzle — Macmillan, 1879 (game invented 1877)
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