Efficiently updatable neural network
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In computer strategy games, for example in shogi and chess, an efficiently updatable neural network (NNUE, a Japanese wordplay on Nue, sometimes stylised as ƎUИИ) is a neural network-based evaluation function whose inputs are piece-square tables, or variants thereof like the king-piece-square table.[1] NNUE is used primarily for the leaf nodes of the alpha–beta tree.[2]
NNUE was invented by Yu Nasu and introduced to computer shogi in 2018.[3][4] On 6 August 2020, NNUE was for the first time ported to a chess engine, Stockfish 12.[5][6] Since 2021, many of the top rated classical chess engines such as Komodo Dragon have an NNUE implementation to remain competitive.
NNUE runs efficiently on central processing units (CPU) without a requirement for a graphics processing unit (GPU).[7][8] In contrast, deep neural network-based chess engines such as Leela Chess Zero require a GPU.[9][10]
The neural network used for the original 2018 computer shogi implementation consists of four weight layers: W1 (16-bit integers) and W2, W3 and W4 (8-bit). It has 4 fully-connected layers, ReLU activation functions, and outputs a single number, being the score of the board.
W1 encoded the king's position and therefore this layer needed only to be re-evaluated once the king moved. It used incremental computation and single instruction multiple data (SIMD) techniques along with appropriate intrinsic instructions.[3]
See also
[edit]- elmo (shogi engine)
- Stockfish chess engine - The chapter about NNUE features a visualization of NNUE.
- List of chess software
References
[edit]- ^ Gary Linscott (April 30, 2021). "NNUE". GitHub. Retrieved December 12, 2020.
- ^ "Stockfish 12". Stockfish Blog. Retrieved 19 October 2020.
- ^ a b Yu Nasu (April 28, 2018). "Efficiently Updatable Neural-Network-based Evaluation Function for computer Shogi" (PDF) (in Japanese).
- ^ Yu Nasu (April 28, 2018). "Efficiently Updatable Neural-Network-based Evaluation Function for computer Shogi (Unofficial English Translation)" (PDF). GitHub.
- ^ "Introducing NNUE Evaluation". 6 August 2020.
- ^ Joost VandeVondele (July 25, 2020). "official-stockfish / Stockfish, NNUE merge". GitHub.
- ^ "Stockfish FAQ: Can Stockfish use my GPU?". Stockfish. Retrieved 19 January 2025.
- ^ "nnue-pytorch/docs/nnue.md".
- ^ Dominik Klein, Neural Networks for Chess, p. 49
- ^ Monroe, Daniel; Chalmers, Philip A. (2024-10-28), Mastering Chess with a Transformer Model, doi:10.48550/arXiv.2409.12272, retrieved 2024-11-29
External links
[edit]- NNUE on the Chess Programming Wiki.
- NNUE evaluation functions for computer shogi on github.com