Fruit Fly Chess Connectome
A chess policy/value network constrained by the wiring topology of the complete Drosophila larval connectome (Winding et al., Science, 2023).
Repository channels
dev/checkpoints/contains immutable training gates uploaded automatically.prod/model.ptis the manually promoted PyTorch checkpoint. Automation never overwrites production.browser/contains the inference-only ONNX release used by fruitflychess.com.benchmarks/contains reproducible Stockfish-anchored evaluation reports.
The initial production promotion is the best validation checkpoint available at publication time: step 1,170,000, validation loss 2.6849. The currently deployed browser release is separately frozen at step 600,000.
Architecture
- 2,952 neurons and 110,677 fixed connectome edges
- 2,820,249 learned parameters
- 256 sensory neurons and 256 motor neurons
- 8 recurrent steps
- 4,672 move-policy outputs and 3 win/draw/loss outputs
- greedy legal-move selection; no search
Measured strength
| Checkpoint | Stockfish-anchored Elo | Games |
|---|---|---|
| 400K | 1,235 | 160 |
| 500K | 1,288 | 160 |
Ratings combine games against Stockfish 18 limited to 1320, 1600, 1800, and 2000 Elo. Each checkpoint plays 40 games per anchor with colors balanced, 50 ms move time, a 4,000-node cap, and no neural search. These ratings are protocol-specific estimates, not FIDE or Chess.com ratings.
Browser files
The ONNX release excludes optimizer state and unsafe pickle data. Its manifest records SHA-256 hashes for both the model and visualization metadata; the browser verifies those hashes before inference.