ai.planning.propositional
Class ActionType

java.lang.Object
  ai.planning.propositional.ActionType

All Implemented Interfaces:

ActionType<ai.krr.propositions.Atom>

public class ActionType
extends java.lang.Object
implements ActionType<ai.krr.propositions.Atom>

An ActionType represents a class of Actions. ActionTypes correspond to Operators in classical planning. In propositional planning the distinction between an ActionType and an Action is almost non-existent.

Author:

Gerhard Wickler

Field Summary

protected ai.krr.NamedSymbol	name the name of this action type (only used for external reference)
protected ai.krr.propositions.Atom[]	negEffects preconditions, negative and positive effects of this ActionTpye
protected ai.krr.propositions.Atom[]	posEffects preconditions, negative and positive effects of this ActionTpye
protected ai.krr.propositions.Atom[]	preconds preconditions, negative and positive effects of this ActionTpye

Constructor Summary

protected

ActionType(ai.krr.NamedSymbol name, ai.krr.propositions.Atom[] pre, ai.krr.propositions.Atom[] negE, ai.krr.propositions.Atom[] posE) This constructor takes a NamedSymbol representing the name of the ActionType and three Arrays of propositional Atoms representing the preconditions, negative effects (also known as the delete list), and positive effects of this ActionType.

ActionType(ai.krr.NamedSymbol name, java.util.Set<ai.krr.propositions.Atom> pre, java.util.Set<ai.krr.propositions.Atom> negE, java.util.Set<ai.krr.propositions.Atom> posE) This constructor takes a NamedSymbol representing the name of the ActionType and three Sets of propositional Atoms representing the preconditions, negative effects (also known as the delete list), and positive effects of this ActionType.

Method Summary

protected ActionType	clone() This class does not support cloning and an Exception will be thrown if this method is called.
static boolean	dependent(ActionType op1, ActionType op2) This function tests whether the two given ActionTypes are dependent.
boolean	equals(java.lang.Object obj) This function tests whether this and the given action type are equal.
ai.krr.NamedSymbol	getName() This function returns the NamedSymbol representing the name of this ActionType.
ai.krr.propositions.Atom[]	getNegativeEffects() This function returns the negative effects of this ActionTpye.
ai.krr.propositions.Atom[]	getNegativePreconditions() This function returns null as there are no negative preconditions in this representation.
ai.krr.fol.Variable[]	getParameters() This function is not supported as there are no parameters in the propositional representation.
ai.krr.propositions.Atom[]	getPositiveEffects() This function returns the positive effects of this ActionTpye.
ai.krr.propositions.Atom[]	getPositivePreconditions() This function returns the preconditions that must be true in a WorldState before an Action of this type can be applied.
int	hashCode() This function returns a hash value for this action type.
java.lang.String	toString() This function creates a String representation for this ActionType.

Methods inherited from class java.lang.Object

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

Field Detail

name

protected final ai.krr.NamedSymbol name

the name of this action type (only used for external reference)

preconds

protected final ai.krr.propositions.Atom[] preconds

preconditions, negative and positive effects of this ActionTpye

negEffects

protected final ai.krr.propositions.Atom[] negEffects

preconditions, negative and positive effects of this ActionTpye

posEffects

protected final ai.krr.propositions.Atom[] posEffects

preconditions, negative and positive effects of this ActionTpye

Constructor Detail

ActionType

public ActionType(ai.krr.NamedSymbol name,
                  java.util.Set<ai.krr.propositions.Atom> pre,
                  java.util.Set<ai.krr.propositions.Atom> negE,
                  java.util.Set<ai.krr.propositions.Atom> posE)

This constructor takes a NamedSymbol representing the name of the ActionType and three Sets of propositional Atoms representing the preconditions, negative effects (also known as the delete list), and positive effects of this ActionType. Note that the two effect sets must be disjoint.

Parameters:

name - the name of this ActionType

pre - the Set of Atoms constituting preconditions

negE - the Set of Atoms constituting negative effects

posE - the Set of Atoms constituting positive effects

ActionType

protected ActionType(ai.krr.NamedSymbol name,
                     ai.krr.propositions.Atom[] pre,
                     ai.krr.propositions.Atom[] negE,
                     ai.krr.propositions.Atom[] posE)

This constructor takes a NamedSymbol representing the name of the ActionType and three Arrays of propositional Atoms representing the preconditions, negative effects (also known as the delete list), and positive effects of this ActionType. Note that the two effect sets must be disjoint and the Arrays should not contain duplicates.

Parameters:

name - the name of this ActionType

pre - the Atoms constituting preconditions

negE - the Atoms constituting negative effects

posE - the Atoms constituting positive effects

Method Detail

clone

protected ActionType 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

getName

public final ai.krr.NamedSymbol getName()

This function returns the NamedSymbol representing the name of this ActionType.

Specified by:

getName in interface ActionType<ai.krr.propositions.Atom>

Returns:

the name of this ActionType

getParameters

public ai.krr.fol.Variable[] getParameters()
                                    throws java.lang.UnsupportedOperationException

This function is not supported as there are no parameters in the propositional representation. Calling this function will cause an Exception to be thrown.

Specified by:

getParameters in interface ActionType<ai.krr.propositions.Atom>

Returns:

nothing

Throws:

java.lang.UnsupportedOperationException

getNegativePreconditions

public ai.krr.propositions.Atom[] getNegativePreconditions()
                                                    throws java.lang.UnsupportedOperationException

This function returns null as there are no negative preconditions in this representation.

Specified by:

getNegativePreconditions in interface ActionType<ai.krr.propositions.Atom>

Returns:

always null

Throws:

java.lang.UnsupportedOperationException

getPositivePreconditions

public final ai.krr.propositions.Atom[] getPositivePreconditions()

This function returns the preconditions that must be true in a WorldState before an Action of this type can be applied.

Specified by:

getPositivePreconditions in interface ActionType<ai.krr.propositions.Atom>

Returns:

the preconditions associated with this ActionType

getNegativeEffects

public final ai.krr.propositions.Atom[] getNegativeEffects()

This function returns the negative effects of this ActionTpye. Negative effects are deleted from a WorldState in which an Action of this type is applied.

Specified by:

getNegativeEffects in interface ActionType<ai.krr.propositions.Atom>

Returns:

the negative effects associated with this ActionType

getPositiveEffects

public final ai.krr.propositions.Atom[] getPositiveEffects()

This function returns the positive effects of this ActionTpye. Positive effects are added to a WorldState in which an Action of this type is applied.

Specified by:

getPositiveEffects in interface ActionType<ai.krr.propositions.Atom>

Returns:

the positive effects associated with this ActionType

equals

public boolean equals(java.lang.Object obj)

This function tests whether this and the given action type are equal. It returns true iff the two types have the same preconditions, positive effects, and negative effects. Note that the name of the action type is ignored.

Overrides:

equals in class java.lang.Object

Parameters:

obj - the Object this ActionType is compared to

Returns:

whether the two ActionTypes are equivalent

hashCode

public final int hashCode()

This function returns a hash value for this action type.

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 ActionType.

Overrides:

toString in class java.lang.Object

Returns:

the String representing this WorldState

dependent

public static boolean dependent(ActionType op1,
                                ActionType op2)

This function tests whether the two given ActionTypes are dependent. Two ActionTypes are dependent if one deletes a precondition or a positive effect of the other. If there are at most n preconditions, positive, or negative effects defined for either ActionType then the time complexity of this operation is in O(n²).

Parameters:

op1 - the first given ActionType

op2 - the second given ActionType

Returns:

true iff the two types are dependent