1,000 Claude agents redid the Fermat proof in 28.7 hours

Anthropic says 1,000 agents on an early version of Claude Fable 5.2 reproduced its formal proof of Fermat’s Last Theorem in 28.7 hours, without the Prove2Me platform or a researcher steering. It’s one toy run with a head start, since the agents got a sketch of the classical route and proved lemmas from the September formalization.

The September run took a researcher and dozens of agents 11 days. Anthropic itself says the result doesn’t replace tools like Prove2Me, because agents tend to give up on hard problems and misjudge their difficulty.

Each agent ran in a sandbox with no internet, and a classifier blocked none of the team’s tool calls. Shortly after the run, Anthropic added a second monitor that reads the agents’ chain of thought.