Efficiently updatable neural network
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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 pruning{{<</
- {cite web |title=Stockfish 12}} |url=https://blog.stockfishchess.org/post/628172810852925440/stockfish-12 |website=Stockfish Blog |accessdate=19 October 2020}}</ref> While being slower than handcrafted evaluation functions, NNUE does not suffer from the 'blindness beyond the current move' problem.[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, all 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 without a requirement for a graphics processing unit (GPU).
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). 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
- elmo (shogi engine)
- Stockfish chess engine - The chapter about NNUE features a visualization of NNUE.
- List of chess software
References
- ^ Gary Linscott (April 30, 2021). "NNUE". Retrieved December 12, 2020.
- ^ "Stockfish - Chessprogramming wiki". www.chessprogramming.org. Retrieved 2020-08-18.
- ^ 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).
- ^ "Introducing NNUE Evaluation". 6 August 2020.
- ^ Joost VandeVondele (July 25, 2020). "official-stockfish / Stockfish, NNUE merge".
External links
- NNUE on the Chess Programming Wiki.
- NNUE evaluation functions for computer shogi on github.com