Thrawn

Thrawn is a free UCI compliant chess engine that analyzes positions and outputs optimal moves.

Thrawn does not include a graphical user interface (GUI) that is required to display a chessboard and to make it easy to input moves. These GUIs are developed independently from Thrawn and are available online. Some recommended GUIs include:

• CuteChess: https://github.com/cutechess/cutechess
• Arena GUI: http://www.playwitharena.de/
• Scid vs PC: https://scidvspc.sourceforge.net/

Rating/ELO

The Rating of Thrawn is evaluated by CCRL

• Thrawn v2.0: ~2800 ELO
• Thrawn v1.1: ~1900 ELO

Compiling Thrawn

Version v2.1 and later: supports x64 and ARM chips. Can compile for linux, macos, or windows.

Older verions: only supports x64 and windows compilation.

Ensure you have a gcc compiler version 7.3 or later.

Building from source

Run these commands:

git clone https://github.com/feftywacky/Thrawn.git
cd Thrawn
cd src
make # or mingw32-make

To clean the build:

make clean # or mingw32-make clean

Compiling Thrawn v1.1 and older:

git clone https://github.com/feftywacky/Thrawn.git
cd Thrawn
cd src
g++ -std=c++17 -Ofast -flto -o Thrawn *.cpp

Evaluation:

• Thrawn v2.0 and newer uses NNUE
• Thrawn v1.1 uses handcrafted evaluation

TODO

• LOTS of general code clean up
• transposition table bug?
• hash move ordering giving worst results bug
• fixed zero evaluation bug
• nnue incremental update
• train own nnue
• opening book table

Features

• NNUE for evaluation
• Various search optimizations
• Bitboard data structure
• Transposition tables
• Time allocation/Control
• Implements UCI protocol

Updates

• no-hashmove reduction
• reverse futility pruning / static null move pruning
• late move pruning
• fifty-move rule + three-fold repetition detection
• NNUE evaluation
• hash move ordering
• razoring pruning
• transposition table / zobrist hashing
• null move pruning
• late move reduction
• iterative deepening (also adjusting aspiration window)
• principal variation search
• move history (quiet and killer)
• quiescence search
• negamax alpha beta search
• piece table evaluation
• uci compliant
• passes perft test! <3

References

General

• https://www.chessprogramming.org/Main_Page
• https://github.com/bluefeversoft/vice
• https://github.com/official-stockfish/Stockfish
• https://github.com/mkd/gargantua

Search Algorithms

• https://web.archive.org/web/20071006042845/http://www.brucemo.com/compchess/programming/index.htm

NNUE

• https://hxim.github.io/Stockfish-Evaluation-Guide/
  
• nnue probe framework: https://github.com/dshawul/nnue-probe
• nnue dataset https://tests.stockfishchess.org/nns