Claude Formalizes Fermat's Last Theorem in 11 Days With 13 Million Lines of Lean Code
The 11-day result compresses a formalization effort that mathematicians expected to take years, and the breakthrough was the Prove2Me coordination layer, not raw model capability.
Reporting from 1 source: GIGAZINE.
Anthropic says Claude produced a fully machine-verified proof of Fermat's Last Theorem, working nearly autonomously for 11 days and generating about 13 million lines of Lean 4 code. The proof passed Lean's checker and is published on GitHub. A coordination platform called Prove2Me let dozens of Claude agents track which theorems remained to prove.
At 13 million lines, the proof is more than five times the size of Mathlib, the standard Lean mathematics library. Claude proved roughly 33,000 theorems in machine-checkable form over 11 days, and the final proof uses about 29,500 of them.
Early runs failed: dozens of Claude agents lost track of the project's progress and could not reuse each other's results. Anthropic researcher Tianyi Peng and colleagues built Prove2Me, a platform that manages theorem dependencies as a directed acyclic graph so each agent sees what to prove next. Separating statements from proofs sped up compilation, and natural language notes made finished proofs searchable.
The proof depends only on Lean's three standard axioms and contains no "sorry" placeholders. An independent Rust-based Lean kernel, nanoda, checked more than a million declarations without error. Anthropic expects formalized proofs alongside human papers to become common.
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