A team of 1,000 Claude Fable 5.2 agents formalised the proof of Fermat’s Last Theorem in 30 hours, with minimal human intervention.
That claim comes from Anthropic’s launch post for Claude Fable 5.2 and Claude Mythos 5.2, published on 9 November.
An earlier formalisation, by an unreleased research Claude, took 11 days. The same job has gone from 11 days to 30 hours.
Opus 5.5, given the same setup, had completed 26% of the work after 18 hours.
Anthropic also reports that Fable 5.2 solved two open problems in black-hole physics, and that in a hardware test it designed three working electronic devices.
Fable and Mythos are described as the same underlying model. Fable carries cyber and biology safeguards and is open to all users. Mythos access goes through verification programmes for cyber and life sciences.
Pricing is $8 per million input tokens and $40 per million output tokens.
Every result above is Anthropic’s own reporting, not independent testing.
Source: Anthropic, Introducing Claude Fable 5.2 and Claude Mythos 5.2