aima.core.search.adversarial

Interface Game<STATE,ACTION,PLAYER>

Type Parameters:

STATE - Type which is used for states in the game.

ACTION - Type which is used for actions in the game.

PLAYER - Type which is used for players in the game.

All Known Implementing Classes:

ConnectFourGame, TicTacToeGame

public interface Game<STATE,ACTION,PLAYER>

Artificial Intelligence A Modern Approach (3rd Edition): page 165.

A game can be formally defined as a kind of search problem with the following elements:

• S0: The initial state, which specifies how the game is set up at the start.
• PLAYER(s): Defines which player has the move in a state.
• ACTIONS(s): Returns the set of legal moves in a state.
• RESULT(s, a): The transition model, which defines the result of a move.
• TERMINAL-TEST(s): A terminal test, which is true when the game is over and false TERMINAL STATES otherwise. States where the game has ended are called terminal states.
• UTILITY(s, p): A utility function (also called an objective function or payoff function), defines the final numeric value for a game that ends in terminal state s for a player p. In chess, the outcome is a win, loss, or draw, with values +1, 0, or 1/2 . Some games have a wider variety of possible outcomes; the payoffs in backgammon range from 0 to +192. A zero-sum game is (confusingly) defined as one where the total payoff to all players is the same for every instance of the game. Chess is zero-sum because every game has payoff of either 0 + 1, 1 + 0 or 1/2 + 1/2 . "Constant-sum" would have been a better term, but zero-sum is traditional and makes sense if you imagine each player is charged an entry fee of 1/2.

Author:

Ruediger Lunde

Method Summary

Modifier and Type	Method and Description
java.util.List<ACTION>	getActions(STATE state)
STATE	getInitialState()
PLAYER	getPlayer(STATE state)
PLAYER[]	getPlayers()
STATE	getResult(STATE state, ACTION action)
double	getUtility(STATE state, PLAYER player)
boolean	isTerminal(STATE state)

Method Detail

getInitialState

STATE getInitialState()

getPlayers

PLAYER[] getPlayers()

getPlayer

PLAYER getPlayer(STATE state)

getActions

java.util.List<ACTION> getActions(STATE state)

getResult

STATE getResult(STATE state,
                ACTION action)

isTerminal

boolean isTerminal(STATE state)

getUtility

double getUtility(STATE state,
                  PLAYER player)