HumanChess 1250-1350 Blitz Checkmates
HumanChess 1250-1350 Blitz Checkmates is a human-move policy model trained by
imitation on Lichess blitz games where both players were rated 1250-1350. The
dataset contains complete games ending in checkmate. This is a policy-only
network without search or a value head.
This release contains the epoch-5 FP32 PyTorch training checkpoint and a
standalone, statically quantized INT8 TorchScript model for x86 CPU inference.
Files
| File | Format | Use |
|---|
checkpoints/cnn-128x6-1250-1350-blitz-checkmates-epoch005.pt | PyTorch FP32 checkpoint | Model, optimizer, and training metadata |
artifacts/cnn-128x6-1250-1350-blitz-checkmates-epoch005-int8.ts | INT8 TorchScript | Compact x86 CPU inference model |
The FP32 training checkpoint is approximately 525 MB, including optimizer
state. The standalone INT8 artifact is approximately 44 MB.
Architecture
- CNN policy network with 128 channels and 6 residual blocks
- Input:
19 x 8 x 8 board tensor
- Output: fixed move-vocabulary logits, masked to legal moves at inference
- Saved epoch: 5
Validation
Full epoch-5 validation metrics:
| Metric | Value |
|---|
| NLL | 1.7104 |
| Perplexity | 5.531 |
| Top-1 accuracy | 46.78% |
| Top-3 accuracy | 74.73% |
| Top-5 accuracy | 84.91% |
INT8 quantization
On an 8,192-position comparison sample:
| Metric | FP32 | INT8 |
|---|
| NLL | 1.7352 | 1.7496 |
| Top-1 accuracy | 45.95% | 45.70% |
| Top-3 accuracy | 74.19% | 73.90% |
| Top-5 accuracy | 84.36% | 84.27% |
Raw-logit argmax agreement was 84.74%. In a color-balanced 100-game match at
temperature 0.5 with the first six plies sampled, FP32 scored 51%: 44 wins, 42
losses, and 14 draws. The estimated FP32 advantage was 7 Elo with a 64-Elo
error margin, making the playing-strength difference statistically
indistinguishable from zero.
Inference
Load the FP32 checkpoint with the HumanChess UCI application:
1human-chess-uci \
2 --checkpoint checkpoints/cnn-128x6-1250-1350-blitz-checkmates-epoch005.pt \
3 --device cpu
Load the standalone INT8 model with --torchscript:
1human-chess-uci \
2 --checkpoint artifacts/cnn-128x6-1250-1350-blitz-checkmates-epoch005-int8.ts \
3 --torchscript \
4 --device cpu
Tournament play used --temperature 0.5 --sample-plies 6.
Limitations
- Policy-only: no search and no value evaluation.
- Trained on a narrow rating and time-control distribution.
- The INT8 artifact is intended for x86 CPU execution.
- Tournament Elo differences are relative, not absolute human or engine ratings.
