---
license: gpl-3.0
tags:
  - chess
  - nnue
  - uci
---

# GaiaChess NNUE networks

Neural networks (NNUE) for the [GaiaChess](https://github.com/jromang/gaiachess) UCI chess engine.

Files are append-only: a network file, once published, is never modified — engine releases pin an exact file name.

## Architectures

Two incompatible generations live here. Each network carries a 16-byte integrity footer
(architecture hash + content hash) and the engine refuses, loudly, a network whose
architecture is not the one it was built for — so a file from one generation cannot be fed
to an engine built for the other.

**GaiaNet T1** (`gaianet-t1-*`, `gaianet-t2-*`, `gaianet-t3*`) — 12 king buckets × 768 PST
inputs + filtered threat features (~41K inputs) → 640 → CReLU + pairwise → 16 → 32 → 1,
8 output buckets.

**GaiaNet T2b** (`gaianet-t2b-*`) — the current generation. 12 king buckets × 768 PST inputs
(i16 rows) plus 64,368 auxiliary features in i8 rows: 4,560 pawn pairs and 59,808 filtered
piece-interaction (threat) features, accumulated into a 1024-wide layer → paired SCReLU →
16 → 32 → 1, with 8 material-based output buckets and a PSQT head. 87 MB per file.

Trained with [Bullet](https://github.com/jw1912/bullet) (T1) and the in-house trainer (T2b),
on Leela T80 positions and self-play data.

## Networks

| File | Architecture | Engine version | Notes |
|------|--------------|----------------|-------|
| `gaianet-t1-1000.bin` | T1 | never shipped | archived for reproducibility: this network generated part of the training data used by its successors |
| `gaianet-t2-1000.bin` | T1 | 4.2.0 – 4.2.5 | previous default network |
| `gaianet-t3b-1000.bin` | T1 | unreleased | +12.0 ±9.5 Elo vs t2 (SPRT, 2588 games) |
| `gaianet-t3e-1100.bin` | T1 | unreleased | t3b fine-tuned for 100 more superbatches at lr/10 |
| `gaianet-t3e-1100b.bin` | T1 | unreleased | last T1 default: same weights as t3e-1100 plus the 16-byte integrity footer |
| `gaianet-t2b-e013.bin` | **T2b** | unreleased (default in `main`) | current default network. Fine-tune of the T2b line on 62 GB of Leela T80 2024 positions, 60 superbatches at lr 1e-4 cosine. +25.4 ±9.7 Elo vs its parent (SPRT) |

## Usage

Networks are embedded into the engine at build time:

```bash
curl -L -o nets/gaianet-t2b-e013.bin \
  "https://huggingface.co/jromanghf/gaiachess-networks/resolve/main/gaianet-t2b-e013.bin"
MODEL=nets/gaianet-t2b-e013.bin RUSTFLAGS="-C target-cpu=native" \
  cargo build --release --features nnue
```

Or loaded at runtime through UCI: `setoption name EvalFile value <path>`.

## License

GPL-3.0-or-later, same as the engine.