Anthropic model formalizes Fermat's Last Theorem in Lean in 11 days, 13.4M lines of proof
sammcallister · x · 2026-09-05
Mathematician Kevin Buzzard (Xena project) confirms an internal Anthropic model, via the prove2.me platform, produced a complete Lean formalization of Fermat's Last Theorem in just 11 days — closing out Freek Wiedijk's famous list of 100 formalization challenges.
- Proof route: the 1995 Darmon–Diamond–Taylor exposition of the Wiles–Taylor–Wiles argument, via Langlands–Tunnell and Ribet's level-lowering; the repo develops Fontaine theory and enough of Mazur's Eisenstein ideal work.
- Scale & verification: over 13.4 million lines of Lean; compiles 20x slower than mathlib on a 96-core machine. Buzzard compiled it and ran a comparator — it checks out. Combined with prior regular-prime formalizations, the result stands.
- Significance: AI autoformalization artifacts are now robust enough to be built upon, spanning algebra, harmonic analysis, geometry and number theory.
Related event: Claude Produces First Formalized Proof of Fermat's Last Theorem in 11 Days(52 posts)→
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