edu.lhup.ai
Class MinMaxAlphaBetaPlayer

java.lang.Object
  |
  +--edu.lhup.ai.MinMaxAlphaBetaPlayer

All Implemented Interfaces:

IPlayer

public class MinMaxAlphaBetaPlayer

extends Object

implements IPlayer

A concrete player that plays any game using the minimax algorithm with alpha-beta pruning and a cutoff. The code used by this player is based on the psuedo code presented in Russell and Norvig's book, "Artificial Intelligence: A Modern Approach". The evaluator used by this player (see setEvaluator(IEvaluator)) is important because it determines how the end states are evaluated during the minimax search.

This software is for educational purposes only.

Author:

Mark Cohen

Field Summary

protected int	m_cutoff
protected IEvaluator	m_evaluator

Constructor Summary

MinMaxAlphaBetaPlayer()

Method Summary

protected boolean	cutoff(IBoard board, int iLevel)
String	getDescription()
protected int	getRating(IBoard board, int level, int alpha, int beta)
String	getShortDescription()
void	setCutoff(int cutoff) Provides a mechanism for specifying the point at which a player's abandons the search for the best move.
void	setEvaluator(IEvaluator evaluator) Provides a mechanism for specifying a player's evaluation strategy.
void	takeTurn(IBoard board) This player makes moves using the minimax algorithm with alpha-beta pruning and a cutoff.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

m_cutoff

protected int m_cutoff

m_evaluator

protected IEvaluator m_evaluator

Constructor Detail

MinMaxAlphaBetaPlayer

public MinMaxAlphaBetaPlayer()

Method Detail

setCutoff

public void setCutoff(int cutoff)

Description copied from interface: IPlayer

Provides a mechanism for specifying the point at which a player's abandons the search for the best move.

Specified by:

setCutoff in interface IPlayer

Parameters:

cutoff - an integer limiting the duration of a player's search for the best move

setEvaluator

public void setEvaluator(IEvaluator evaluator)

Description copied from interface: IPlayer

Provides a mechanism for specifying a player's evaluation strategy. By implementing the IEvaluator interface programmers can create their own custom evaluators and request that a player use the evaluator by calling this method.

Specified by:

setEvaluator in interface IPlayer

Parameters:

evaluator - the strategy used by this player in order to evaluate the current game state.

getDescription

public String getDescription()

Specified by:

getDescription in interface IPlayer

Returns:

a description of this player.

getShortDescription

public String getShortDescription()

Specified by:

getShortDescription in interface IPlayer

Returns:

a short description of this player.

toString

public String toString()

Overrides:

toString in class Object

takeTurn

public void takeTurn(IBoard board)
              throws TurnException

This player makes moves using the minimax algorithm with alpha-beta pruning and a cutoff. The evaluator used by this player determines how end states will be evaluated during the minimax search.

Specified by:

takeTurn in interface IPlayer

Parameters:

board - the IBoard object that this player will make a move on.

Throws:

TurnException - if the player attemts to push an invalid move onto the games stack.

cutoff

protected boolean cutoff(IBoard board,
                         int iLevel)

getRating

protected int getRating(IBoard board,
                        int level,
                        int alpha,
                        int beta)
                 throws StateException

StateException