Arasan – cross-platform chess engine

Arasan is a chess engine, that is, a console-based program that plays the game of chess.

By itself, it has no graphical interface, but can be used together with interface programs such as XBoard.

Arasan is published under an open source license.

Arasan means “king” in Tamil, a language spoken in South India and Sri Lanka. It is related to the Sanskrit word “raja.”

Features include:

• Use “magic” bitboards logic instead of rotated bitboards with an accompanying 20-25% increase in performance.
• Performs PEXT/PDEP Bitboards to replace Fancy Magic Bitboards in looking up sliding piece attacks.
• Search:
  • Lazy SMP 21.0.
  • Iterative Deepening Depth Resolution 4.
  • Aspiration Windows.
  • Principal Variation Search.
  • Transposition Table:
    • Shared Hash Table.
    • Lockless Hashing.
  • Move Ordering:
    • Internal Iterative Deepening.
    • Countermove Heuristic.
    • Counter Moves History.
    • Killer Heuristic.
    • Refutation Table.
    • History Heuristic.
    • MVV/LVA.
    • SEE.
  • Selectivity:
    • Fractional Ply Extensions:
      • Check Extensions.
      • Passed Pawn Extensions.
      • Singular Extensions.
    • Pruning:
      • Null Move Pruning.
      • Static Null Move Pruning.
      • SEE Pruning.
      • Futility Pruning.
      • Late Move Pruning.
      • ProbCut.
    • Reductions:
      • Late Move Reductions.
      • Razoring.
    • Quiescence Search.
• Evaluation:
  • Material.
  • Piece-Square Tables.
  • Development.
  • Mobility:
    • Trapped Pieces.
    • Rooks on (Semi) Open Files.
  • Outposts.
  • Pawn Structure:
    • Pawn Hash Table.
    • Backward Pawn.
    • Doubled Pawn.
    • Isolated Pawn.
  • Passed Pawn:
    • Connected Passed Pawns.
    • Outside Passed Pawn.
    • Blockade of Stop.
    • Tarrasch Rule.
  • King Safety:
    • King Tropism.
    • Pawn Shelter.
    • Pawn Storm.
• Supports a strength limitation option.
• Cross-platform support – runs under Linux, Mac OS, and Windows.

Website: www.arasanchess.org
Support: GitHub Code Repository
Developer: Jon Dart
License: MIT License

Arasan is written in C++. Learn C++ with our recommended free books and free tutorials.

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