Yes — with an important caveat. On September 4, 2026, Anthropic announced that Claude produced the first complete computer-checked formalization of Fermat’s Last Theorem in the Lean proof assistant, working largely autonomously over about 11 days. The result is a machine-verifiable encoding of Andrew Wiles’s 1995 proof (via a Darmon–Diamond–Taylor exposition), not a brand-new discovery of the theorem itself.
Along the way Claude wrote roughly 13 million lines of Lean and proved about 29,500 intermediate theorems used in the final proof, relying only on Lean’s standard axioms. Imperial College London mathematician Kevin Buzzard, who has led a human formalization effort, reviewed the work and said it proves the theorem with no assumptions other than the axioms of mathematics.