Introduction

Since the variant NNUE training code is based on https://github.com/glinscott/nnue-pytorch, you can also have a look at its documentation for additional information. However, keep in mind that official Stockfish already switched to different architectures, so architecture related information might not apply here. Fairy-Stockfish still uses a HalfKAv2 based NNUE architecture. Furthermore Fairy-Stockfish uses a generalized bin training data format (with 512 instead of 256 bit) incompatible with the official Stockfish trainer.

Training data generation

There is training data generation code based on different engines

• Fairy-Stockfish (all variants): https://github.com/ianfab/Fairy-Stockfish/tree/tools
• YaneuraOu (for Shogi): https://github.com/ianfab/YaneuraOu/tree/fairy_bin
• NewGG (for Xiangqi): https://github.com/ianfab/NewGG/tree/gensfen (work in progress)

NNUE training

In order to run NNUE training for specific variants, the code requires minor adjustments to specify board size, piece types, etc. See the branches for specific variants in order to identify the typical required changes. Remember to always recompile the training data loader after such adjustments.