aima.core.search.informed

Class BestFirstSearch

java.lang.Object

aima.core.search.framework.PrioritySearch

aima.core.search.informed.BestFirstSearch

All Implemented Interfaces:

SearchForActions, SearchForStates

Direct Known Subclasses:

AStarSearch, GreedyBestFirstSearch

public class BestFirstSearch
extends PrioritySearch

Artificial Intelligence A Modern Approach (3rd Edition): page 92.

Best-first search is an instance of the general TREE-SEARCH or GRAPH-SEARCH algorithm in which a node is selected for expansion based on an evaluation function, f(n). The evaluation function is construed as a cost estimate, so the node with the lowest evaluation is expanded first. The implementation of best-first graph search is identical to that for uniform-cost search (Figure 3.14), except for the use of f instead of g to order the priority queue.

Author:

Ciaran O'Reilly, Mike Stampone, Ruediger Lunde

Constructor Summary

Constructors

Constructor and Description
BestFirstSearch(QueueSearch impl, EvaluationFunction ef) Constructs a best first search from a specified search problem and evaluation function.

Method Summary

Modifier and Type	Method and Description
EvaluationFunction	getEvaluationFunction()

Methods inherited from class aima.core.search.framework.PrioritySearch

findActions, findState, getComparator, getMetrics, getNodeExpander

Methods inherited from class java.lang.Object

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

Constructor Detail

BestFirstSearch

public BestFirstSearch(QueueSearch impl,
                       EvaluationFunction ef)

Constructs a best first search from a specified search problem and evaluation function.

Parameters:

impl - a search space exploration strategy.

ef - an evaluation function, which returns a number purporting to describe the desirability (or lack thereof) of expanding a node.

Method Detail

getEvaluationFunction

public EvaluationFunction getEvaluationFunction()