net.sf.genethello.gametheory
Interface Board

All Known Implementing Classes:

Board

public interface Board

Interface to simulate board of game.

Author:

Administrator

Method Summary

long	getZobristKey() Get Zobrist key, a long number reflecting a board position to be used for faster and more space efficient transposition tables and opening books. To use this feature, the following should be done: Declares transpositionMaxIndex to be (power of two) - 1 somewhere in program initialization. e.g.
boolean	isUnquiet() Indicates that a position is not in quiescence state, i.e.
void	updateZobristKeyOnTurn(int turn) Updates zobrist key when turn changes.

Method Detail

getZobristKey

long getZobristKey()

Get Zobrist key, a long number reflecting a board position to be used for faster and more space efficient transposition tables and opening books.

To use this feature, the following should be done:

• Declares transpositionMaxIndex to be (power of two) - 1 somewhere in program initialization.
  e.g. transpositionMaxIndex = (long) (Math.pow(2, 20) - 1);
• Declares array of transpositionTable with size transpositionMaxIndex + 1
  e.g. transpositionTable = new TranspositionTable[(int) transpositionMaxIndex + 1];
• Defines and declares zobristKey
  e.g. private long zobristKey = 0;
• Defines and initializes zobrist values used to construct zobristKey.
  e.g. (in case of othello game)
  zobrist values for each color in each square:
  private long[][] zsquares = new long[Constants.SQNUM][2];
  

    Random rnd = new Random();
    for (int i = 0; i < Constants.SQNUM; i++) {
        for (int j = 0; j < 2; j++) {
            zsquares[i][j] = rnd.nextLong();
        }
    }

  zobrist values for each color having turn to move
  private long[] zturn = new long[2];

    zturn[0] = rnd.nextLong();
    zturn[1] = rnd.nextLong();
    zobristKey = 0;

• Updates zobristKey according to board position and turn using ^ (XOR) operator, tipically inside the implementation of methods Generate, UndoGenerate, DoMove, UndoMove of class GameTheory.
  e.g. (in case of othello game)
  zobristKey ^= zsquares[index][turn];
zobristKey ^= zturn[turn];
• Implements this method
  e.g. return zobristKey;

Returns:

Zobrist key

updateZobristKeyOnTurn

void updateZobristKeyOnTurn(int turn)

Updates zobrist key when turn changes.

Parameters:

turn -

isUnquiet

boolean isUnquiet()

Indicates that a position is not in quiescence state, i.e. the horizon effect is large.

Returns:

true if state is not quiescence, or false otherwise