ai.search
Class Problem

java.lang.Object
  ai.search.Problem

All Implemented Interfaces:

java.awt.event.ActionListener, java.util.EventListener, java.lang.Runnable

Direct Known Subclasses:

CannibalProblem, ChainProblem, Puzzle8Problem, RouteProblem

public abstract class Problem

extends java.lang.Object

implements java.lang.Runnable, java.awt.event.ActionListener

An abstract search problem.

Author:

Jill Zimmerman -- jill.zimmerman@goucher.edu

Field Summary

java.lang.String	algorithm The search algorithm.
java.awt.Canvas	canvas canvas to display the search.
Node	currentNode The current node in the search.
boolean	display Whether or not to display the search.
java.lang.Object	goal An optional goal state.
java.lang.String	heuristic The search heuristic.
java.lang.Object	initialState The initial state.
int	numExpanded The number of nodes expanded in the search.
java.util.Vector	q The search queue.
Search	search The search.
Node	searchResult The node which is the search result.

Constructor Summary

Problem(java.lang.Object initState)

Method Summary

void	actionPerformed(java.awt.event.ActionEvent e)
abstract java.lang.String	actionToString(java.lang.Object action) Convert an action to a string.
int	edgeCost(Node node, java.lang.Object action, java.lang.Object state) Return the cost of an edge.
abstract boolean	equalState(java.lang.Object state1, java.lang.Object state2) Determine if two states are equivalent.
boolean	goalReached(java.lang.Object state) Is the state a goal state?
int	hCost(java.lang.Object state) Return the estimated cost from given state to a goal.
void	run()
Node	solve(java.lang.String alg, java.lang.String heur, int maxExpanded) Solve the problem with the specified search algorithm.
void	start()
abstract java.lang.String	stateToString(java.lang.Object state) Convert a state to a string.
void	stop()
abstract java.util.Vector	successors(java.lang.Object state) Determine all the states which are successors of the given state.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

initialState

public java.lang.Object initialState

The initial state.

goal

public java.lang.Object goal

An optional goal state.

numExpanded

public int numExpanded

The number of nodes expanded in the search.

display

public boolean display

Whether or not to display the search.

canvas

public java.awt.Canvas canvas

canvas to display the search.

q

public java.util.Vector q

The search queue.

search

public Search search

The search.

algorithm

public java.lang.String algorithm

The search algorithm.

heuristic

public java.lang.String heuristic

The search heuristic.

searchResult

public Node searchResult

The node which is the search result.

currentNode

public Node currentNode

The current node in the search.

Constructor Detail

Problem

public Problem(java.lang.Object initState)

Method Detail

successors

public abstract java.util.Vector successors(java.lang.Object state)

Determine all the states which are successors of the given state.

Parameters:

state - is the given state

Returns:

a vector of successors

equalState

public abstract boolean equalState(java.lang.Object state1,
                                   java.lang.Object state2)

Determine if two states are equivalent.

Parameters:

state1 - and states are the two states

Returns:

true if equal

stateToString

public abstract java.lang.String stateToString(java.lang.Object state)

Convert a state to a string.

Parameters:

state - is the given state

Returns:

a string expressing the state

actionToString

public abstract java.lang.String actionToString(java.lang.Object action)

Convert an action to a string.

Parameters:

action - is the given action

Returns:

a string expressing the action

goalReached

public boolean goalReached(java.lang.Object state)

Is the state a goal state?

hCost

public int hCost(java.lang.Object state)

Return the estimated cost from given state to a goal. A default value is 0.

edgeCost

public int edgeCost(Node node,
                    java.lang.Object action,
                    java.lang.Object state)

Return the cost of an edge. A default value is 1.

start

public void start()

stop

public void stop()

run

public void run()

Specified by:

run in interface java.lang.Runnable

solve

public Node solve(java.lang.String alg,
                  java.lang.String heur,
                  int maxExpanded)

Solve the problem with the specified search algorithm.

Parameters:

alg - is the algorithm.

heur - is an optional heuristic

maxExpanded - is the maximum number of nodes to expand

Returns:

the node of a solution.

actionPerformed

public void actionPerformed(java.awt.event.ActionEvent e)

Specified by:

actionPerformed in interface java.awt.event.ActionListener