amoeba

an UCI chess engine in D language

How to use it

Amoeba is a bare chess engine designed to communicate with a chess GUI (like xboard/winboard, arena, ...) via the UCI protocol. For example, xboard -fcp amoeba -fd installation directory -fUCI with:

• amoeba the name of the executable
• installation directory the directory where is the executable

About the program

When I wrote this chess engine, I tried to stay as close as possible to the published algorithms. I hope my code to be easy to read & understand.

• algorithms used for move generation (board.d)

  • bitboard / mailbox board representation;
  • hyperbola quintessence;
  • stage move generation

• algorithms used in search (search.d)

  • transposition table;
  • principal variation search;
  • quiescence search;
  • late move reduction (LMR);
  • in check extension;
  • null move;
  • frontier node pruning & razoring;
  • delta pruning in quiescence search;
  • internal iterative deepending (IID);
  • aspiration window;
  • iterative deepening;
  • static exchange evaluation (see) - iterative version;
  • singular move extension
  • probcut

• algorithms used in evaluation

  • tuned weights with the "Nelder-Mead simplex method", aka amoeba (so the name of the program);
  • lazy evaluation using material + positional + tempo data;
  • full evaluation using various mobility scores & pawn structures in addition to the lazy evaluation; So, the chess knowledge is still very basic and could be improved significantly.

• algorithm tried but discarded:

  • enhanced transposition cutoff (ETC);
  • ...