On July 24, Anthropic's Claude Opus 5 cleared the highest score ever recorded on ARC-AGI-3, scoring 30.2% — nearly quadrupling GPT-5.6 Sol's previous record of 7.8%, per the ARC Prize results page. While doing so, it wrote an algebraic equation that no frontier model had ever produced, according to ARC Prize's independently administered results. The equation, generated spontaneously at action 23 of one environment, read: 4_center = 2×axis − 5_center. ARC Prize called it the first explicit reflection equation from any model in their analysis, as documented in their official July 24 announcement. Opus 5 solved five environments no AI had previously beaten, four of them at or above human efficiency, and pushed the total number of solved public demo environments from one to six, as confirmed in ARC Prize's July 24 X post. Anthropic's own prior generation — Fable-class models — reached approximately 20%, according to ARC Prize. ARC-AGI-3, which launched in March 2026 at Y Combinator in San Francisco, is a turn-based interactive game where agents must explore to learn each environment's rules without instructions, language, or domain knowledge, using only Core Knowledge priors. Performance is measured by a metric called RHAE — Relative Human Action Efficiency.