Anthropic says Claude writes longest proof of Fermat's Last Theorem

Anthropic says Claude formally proved Fermat's Last Theorem in 11 days. Anthropic says the result is the longest mathematical proof ever written. The proof contains 13 million lines of code that computers can check line by line. Fermat's Last Theorem had stumped mathematicians for 358 years. Kevin Buzzard reviewed the proof and said it proves the theorem with no assumptions beyond the axioms of mathematics. The work formalized Andrew Wiles's proof from 1995 rather than discovering new mathematics. Dozens of Claude agents worked in parallel with almost no human input beyond occasional instructions. An early phase produced false starts that account for about 7% of the final proof's lines. Peng's team used the Prove2Me tool to coordinate the agents and prevent duplicated work. Claude proved more than 30,000 supporting theorems and used billions of tokens. The proof is more than five times the size of Mathlib. Imperial College London mathematician Kevin Buzzard began a project in 2024 to translate Wiles's proof into Lean. The project is funded through 2029. The full proof is available on GitHub for mathematicians to inspect.