AI reasoning

According to testing firm Vals AI, Anthropic's Claude Fable 5.1 independently identified and solved the 'Cyphral Distich,' a 1653 numeric cipher by Sir Thomas Urquhart that had defeated other frontier models. The AI decoded a hidden pro-royalist message by mapping each number to a word in Urquhart's original text.

Claude Opus 5 scored 30.2 percent on the ARC-AGI-3 benchmark, nearly four times the previous record of 7.8 percent set by OpenAI's GPT-5.6 Sol (Max). The ARC Prize team attributes the leap to genuinely stronger reasoning, though an independent test on a separate puzzle benchmark showed far smaller improvements.