Claude formalizes Fermat's Last Theorem autonomously in 11 days, 13M lines of Lean

rohanpaul_ai · x · 2026-09-05

Anthropic shared the first complete computer-checked proof of Fermat's Last Theorem, produced by Claude working largely autonomously over 11 days in the Lean language—writing 13 million lines of code and proving 29,500 intermediate theorems. The effort built on Wiles's 129-page 1995 proof and a community formalization project started by Kevin Buzzard in 2024; Anthropic researcher Tianyi Peng set up the experiment, and Buzzard called it an extraordinary autoformalization achievement.

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