Claude formalizes Fermat's Last Theorem in 13M-line Lean proof, Anthropic says

Dr_Singularity · x · 2026-09-05

Anthropic says Claude completed the first formalized Lean proof of Fermat's Last Theorem—a project experts expected to take years. The proof spans over 13 million lines of code, the largest Lean proof ever written, and along the way formalizes more than 29,000 supporting theorems across math areas never previously formalized, all machine-verified. Fermat's Last Theorem was first classically proven by Andrew Wiles in 1995, 350+ years after it was conjectured.

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