Laser

Laser is a UCI-compliant chess engine written in C++11 by Jeffrey An and Michael An.

The latest release and previous versions can be found here. Compiled binaries for 32 and 64-bit Windows are included.

Laser is a command-line engine only. To have a graphical interface, the executable can be used with any UCI chess GUI, such as Arena or Tarrasch.

Engine Strength

• CCRL 40/4: 11th, 3281 ELO (4 CPU) as of October 21, 2018
• CCRL 40/40: 11th, 3227 ELO (4 CPU) as of October 24, 2018

Makefile Notes

The code and Makefile support g++ on Linux and MinGW on Windows for popcnt processors only. For older or 32-bit systems with no popcnt instruction support, use the NOPOPCNT=true option. To compile, simply run make in the main directory. The USE_STATIC=true option creates a statically-linked build with all necessary libraries.

Thanks To:

• The Chess Programming Wiki, which is a great resource for beginner chess programmers, and was consulted frequently for this project
• The authors of Stockfish, Crafty, EXChess, Rebel, Texel, and all other open-source engines for providing inspiration and great ideas to move Laser forward
• The engine testers and rating lists, for uncovering bugs, providing high quality games and ratings, and giving us motivation to improve
• Cute Chess, the primary tool used for testing

Implementation Details

• Lazy SMP up to 128 threads
• Fancy magic bitboards for a 4.5 sec PERFT 6 @2.2 GHz (no bulk counting).
• Evaluation
  • Tuned with reinforcement learning, coordinate descent, and a variation of Texel's Tuning Method
  • Piece square tables
  • King safety, pawns shields and storms
  • Isolated/doubled/passed/backwards pawns
  • Mobility
  • Outposts
  • Basic threat detection and pressure on weak pieces
• A two-bucket transposition table with Zobrist hashing, 16 MB default size
• An evaluation cache
• Syzygy tablebase support
• Fail-soft principal variation search
  • Adaptive null move pruning, late move reduction
  • Futility pruning, razoring, move count based pruning (late move pruning)
  • Check and singular extensions
• Quiescence search with captures, queen promotions, and checks on the first two plies
• Move ordering
  • Internal iterative deepening when a hash move is not available
  • Static exchange evaluation (SEE) and Most Valuable Victim / Least Valuable Attacker (MVV/LVA) to order captures
  • Killer and history heuristics to order quiet moves

To Dos

• Enumerate or typedef basic values such as color, piece type, and scores
• Chess960 support
• Improved pruning rules
• More efficient PERFT and eval