ai.planning.strips
Class Problem

java.lang.Object
  ai.planning.strips.Problem

All Implemented Interfaces:

Problem<ai.krr.fol.Atom>, inf.compilers.SyntaxAdaptable

public class Problem
extends java.lang.Object
implements Problem<ai.krr.fol.Atom>, inf.compilers.SyntaxAdaptable

A planning problem over a planning Domain is defined by an initial WorldState and a Goal. A SequentialPlan is a solution to such a planning problem if and only if its execution in the initial state results in a state in which the goal is satisfied.

Author:

Gerhard Wickler

Nested Class Summary

protected static class

Problem.ObjectTypeSystem

Field Summary

protected Domain	domain the Domain over which this problem is defined
protected Goal	goal the goal condition to be achieved
protected WorldState	initialState the initial state of the world
protected ai.krr.NamedSymbol	name the reference String that can be used to refer to this problem
protected Problem.ObjectTypeSystem	types the inferred DomainTypes for objects in this Problem (computed on demand)

Constructor Summary

Problem(Domain d, WorldState s0, Goal g)
This constructor creates a new planning problem over the given domain.

Method Summary

protected Problem	clone() This class does not support cloning and an Exception will be thrown if this method is called.
boolean	equals(java.lang.Object obj) This function tests whether this and the given problem are the same Object.
Domain	getDomain() This function returns the domain over which this Problem is defined.
Goal	getGoal() This function returns the goal conditions that define this Problem.
WorldState	getInitialState() This function returns the initial state of the world that defines this Problem.
java.util.Set<ai.krr.NamedSymbol>	getInstances(Domain.DomainType type)
protected Problem.ObjectTypeSystem	getObjectTypeSystem() This function returns the inferred types for this Domain.
int	hashCode() This function returns a hash value for this problem.
protected java.lang.String	objectString() This function returns a String that is the String returned by this Object's toString function.
void	prettyPrint(int indent, java.io.Writer w, inf.compilers.SyntaxAdaptor sa) This function can be used write this SyntaxAdaptable object to the given Writer.
static Problem	read(java.io.Reader r, inf.compilers.SyntaxAdaptor<Problem> sa)
java.lang.String	toString() This function creates a String representation for this Problem.
void	write(java.io.Writer w, inf.compilers.SyntaxAdaptor sa) This function can be used write this logical Sentence to the given Writer.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

domain

protected Domain domain

the Domain over which this problem is defined

initialState

protected WorldState initialState

the initial state of the world

goal

protected Goal goal

the goal condition to be achieved

name

protected ai.krr.NamedSymbol name

the reference String that can be used to refer to this problem

types

protected Problem.ObjectTypeSystem types

the inferred DomainTypes for objects in this Problem (computed on demand)

Constructor Detail

Problem

public Problem(Domain d,
               WorldState s0,
               Goal g)

This constructor creates a new planning problem over the given domain.

Parameters:

d - the domain over which the problem is defined

s0 - the initial state of the world

g - the goal to be achieved

Method Detail

clone

protected Problem clone()
                 throws java.lang.CloneNotSupportedException

This class does not support cloning and an Exception will be thrown if this method is called.

Overrides:

clone in class java.lang.Object

Returns:

nothing

Throws:

java.lang.CloneNotSupportedException - will be thrown

getDomain

public Domain getDomain()

This function returns the domain over which this Problem is defined.

Specified by:

getDomain in interface Problem<ai.krr.fol.Atom>

Returns:

the Domain underlying this Problem

getInitialState

public WorldState getInitialState()

This function returns the initial state of the world that defines this Problem.

Specified by:

getInitialState in interface Problem<ai.krr.fol.Atom>

Returns:

the WorldState assumed to hold initially

getGoal

public Goal getGoal()

This function returns the goal conditions that define this Problem.

Specified by:

getGoal in interface Problem<ai.krr.fol.Atom>

Returns:

the Goal that is to be achieved in this Problem

write

public void write(java.io.Writer w,
                  inf.compilers.SyntaxAdaptor sa)
           throws inf.compilers.ExpressivenessException,
                  java.io.IOException

This function can be used write this logical Sentence to the given Writer. The syntax in which it is written is defined by the SyntaxAdaptor that is also given to this function.

Specified by:

write in interface inf.compilers.SyntaxAdaptable

Parameters:

w - the Writer to which this Sentence is written

sa - the SyntaxAdaptor that determines the syntax

Throws:

inf.compilers.ExpressivenessException - if the syntax does not support every construct occurring in this Sentence

java.io.IOException - if writing to the Writer fails

prettyPrint

public void prettyPrint(int indent,
                        java.io.Writer w,
                        inf.compilers.SyntaxAdaptor sa)
                 throws inf.compilers.ExpressivenessException,
                        java.io.IOException

This function can be used write this SyntaxAdaptable object to the given Writer. The syntax is the same as for normal writing. The only difference is the inclusion of extra space and newlines for better readability.

Specified by:

prettyPrint in interface inf.compilers.SyntaxAdaptable

Parameters:

indent - the amount of indentation for the first line

w - the Writer to which this Sentence is written

sa - the SyntaxAdaptor that determines the syntax

Throws:

inf.compilers.ExpressivenessException - if the syntax does not support every construct occurring in this Sentence

java.io.IOException - if writing to the Writer fails

getInstances

public java.util.Set<ai.krr.NamedSymbol> getInstances(Domain.DomainType type)

getObjectTypeSystem

protected Problem.ObjectTypeSystem getObjectTypeSystem()

This function returns the inferred types for this Domain. These will have to be computed the first time this function is called, but are then stored for future re-use.

Returns:

the DomainTypes that can be created for this Domain

objectString

protected java.lang.String objectString()

This function returns a String that is the String returned by this Object's toString function. Note that this makes it unique to this Problem.

String a unique String for this Problem

equals

public boolean equals(java.lang.Object obj)

This function tests whether this and the given problem are the same Object.

Overrides:

equals in class java.lang.Object

Parameters:

obj - the Object this Problem is compared to

Returns:

whether they are identical

hashCode

public int hashCode()

This function returns a hash value for this problem.

Overrides:

hashCode in class java.lang.Object

Returns:

an integer that can be used for hashing

toString

public java.lang.String toString()

This function creates a String representation for this Problem.

Overrides:

toString in class java.lang.Object

Returns:

the String representing this Problem

read

public static Problem read(java.io.Reader r,
                           inf.compilers.SyntaxAdaptor<Problem> sa)
                    throws inf.compilers.ExpressivenessException,
                           java.text.ParseException,
                           java.io.IOException

Throws:

inf.compilers.ExpressivenessException

java.text.ParseException

java.io.IOException