Anthropic: 1,000 Fable 5.2 agents complete formalization of Fermat's Last Theorem in 30 hours; Opus 5.5 achieves only 26%.

Anthropic officially announced that a team of 1,000 Fable 5.2 agents completed the full formalization of Fermat's Last Theorem within 30 hours, translating the proof into a language verifiable by computers step-by-step. Under the same setup, Opus 5.5 achieved only 26% completion in 18 hours and made little progress after 30 hours; charts show Fable 5.2 paused at 0.86 completion after 18 hours, resumed 12 hours later, and reached 1.00 final completion, while Opus 5.5 ended at 0.27.