Model
claude-fable-5.1
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- Models & capabilities 5
- Benchmarks & progress 3
- Ideas & essays 1
- Safety & alignment 1
- Security & misuse 1
Anthropic says Claude computed a nine-loop physics amplitude
Working largely unsupervised over several days, the model extended a calculation of particle-scattering formulas one loop past the previous 2023 record, for an estimated $1,000-2,000 of compute.
Models & capabilities · Ideas & essays
Anthropic releases Claude Opus 5.5
Anthropic said Opus 5.5 matches Fable 5.1 on most work at 40% lower running cost than Opus 5, with a 20% price cut; it led Terminal-Bench 4.0 and Artificial Analysis's GDPval-AA board.
Models & capabilities · Benchmarks & progress
OpenAI releases GPT-6 Astra
OpenAI's flagship is its first model rated 'Critical' for cyber capability, and its launch is shadowed by disclosures that a 'recurrent depth' technique makes Astra's reasoning harder to monitor.
Models & capabilities · Safety & alignment · Security & misuse
Anthropic releases Claude Fable 5.1 and Claude Mythos 5.1
Anthropic's launch table put Fable 5.1 ahead of its own Fable 5 and Opus 5 and OpenAI's GPT-5.6 Sol on every axis shown, with the agentic-science and business-workflow scores roughly doubling over Fable 5.
Models & capabilities · Benchmarks & progress
Claude Fable 5.1 solves a 370-year-old cipher in a Vals AI test
Given only the puzzle, Anthropic's model recovered the plaintext of Sir Thomas Urquhart's unsolved 1653 cipher in 44 minutes and 176,000 tokens, then checked its answer against the couplet's own structure.
Models & capabilities · Benchmarks & progress