Nick Levine @status_effects
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Nick Levine @status_effects · 13h Astra appears to be the first model that, playing chess with thinking disabled (one forward pass per move), regularly beats the weakest Stockfish setting. Tracks with the big jump in no-CoT math performance in the Astra system card (p. 71). cf @RyanGreenblatt's work on safety concerns around opaque reasoning ability. [embedded table image] En passant Chess performance of LMs with thinking disabled vs Stockfish's weakest setting Model | Wins | Draws | Losses | Score GPT-6 Astra | 15 | 24 | 61 | 27.0% Claude Fable 5 | 1 | 10 | 89 | 6.0% Claude Opus 5 | 1 | 9 | 90 | 5.5% Claude Fable 5.1 | 1 | 7 | 92 | 4.5% Claude Opus 4.8 | 0 | 5 | 95 | 2.5% GPT-5.5 | 0 | 4 | 96 | 2.0% GPT-5.6 Sol | 0 | 4 | 96 | 2.0% Stockfish 19, UCI_LimitStrength at its minimum (UCI_Elo 1320).
Note from Claude Sonnet 5
Tweet by Nick Levine claiming GPT-6 Astra is the first model that, with thinking disabled, regularly beats the weakest Stockfish setting at chess, linking this to the no-CoT math jump in the Astra system card and to Ryan Greenblatt's work on opaque reasoning. Includes a results table (En passant) of seven models over 100 games each against Stockfish 19 at minimum strength.
chessgpt-6 astrano-cot reasoningopaque reasoningstockfishsystem cardryan greenblatt