Package org.tweetyproject.lp.asp.syntax

Class ASPRule

java.lang.Object

org.tweetyproject.lp.asp.syntax.ASPElement

org.tweetyproject.lp.asp.syntax.ASPRule

All Implemented Interfaces:

Comparable<ASPRule>, Formula, Rule<ASPHead,ASPBodyElement>, ComplexLogicalFormula, LogicStructure, SimpleLogicalFormula

public class ASPRule
extends ASPElement
implements Rule<ASPHead,ASPBodyElement>, Comparable<ASPRule>

This class models a rule in ASP. A rule consists of a head and a body. The head contains 0+ classical atoms and the body contains 0+ literals. Rules with non-empty heads and empty bodies are called facts, rules with empty heads and non-empty bodies are called constraints.

Author:

Anna Gessler, Tim Janus, Thomas Vengels

Constructor Summary

Constructors

Constructor	Description
ASPRule()	Empty constructor
ASPRule(List<ASPBodyElement> body)	Creates a constraint with the given body.
ASPRule(List<ASPBodyElement> nafliterals, Term<?> weight, List<Term<?>> terms)	Creates a weak constraint with the given weight and terms.
ASPRule(List<ASPBodyElement> body, Term<?> weight, Term<?> level, List<Term<?>> terms)	Creates a weak constraint with the given weight, level (priority) and terms.
ASPRule(ASPHead head)	Creates a fact with the given ASPHead.
ASPRule(ASPHead head, List<ASPBodyElement> body)	Creates a rule with the given head and body.
ASPRule(ASPHead head, ASPBodyElement b)	Creates a rule with the given head and a single-element body.
ASPRule(ASPLiteral literal)	Creates a fact with the given literal.
ASPRule(ASPLiteral head, List<ASPBodyElement> body)	Creates a rule with the given head and body.
ASPRule(ASPLiteral head, ASPBodyElement b)	Creates a rule with the given head and a single-element body.
ASPRule(ASPRule other)	Copy-Constructor
ASPRule(OptimizationStatement opt)	Creates a new rule with the given optimization statement.

Method Summary

Modifier and Type	Method	Description
void	addBody(ASPBodyElement premise)	Add the given body element to this rule.
void	addBodyElements(Collection<? extends ASPBodyElement> premises)	Add the given body elements to this rule.
void	addPremise(ASPBodyElement premise)	Add the given premise to this rule.
void	addPremises(Collection<? extends ASPBodyElement> premises)	Add the given premises to this rule.
void	addToHead(ASPLiteral literal)	Add the given literal to the head of the rule.
ASPRule	clone()	Creates a deep copy of this formula
int	compareTo(ASPRule arg0)
boolean	equals(Object obj)
ASPRule	exchange(Term<?> v, Term<?> t)	Substitutes all occurrences of term "v" in this formula by term "t" and at the same time replaces all occurrences of term "t" by term "v" and eventually returns the new formula.
Set<ASPAtom>	getAtoms()	Processes the set of all atoms which appear in this formula
List<ASPBodyElement>	getBody()	Return the body of this rule
ASPHead	getConclusion()	Returns the conclusion of this rule.
List<Term<?>>	getConstraintTerms()	Return the constraint terms of this rule.
ASPHead	getHead()	Return head of this rule
Term<?>	getLevel()	Return the level attribute of this constraint.
Collection<? extends ASPLiteral>	getLiterals()	Retrieves all the literals contained within this rule.
Set<Predicate>	getPredicates()	Processes the set of all predicates which appear in this formula
List<ASPBodyElement>	getPremise()	Returns the premise of this rule.
FolSignature	getSignature()	Returns the signature of the language of this formula.
Set<Term<?>>	getTerms()
<C extends Term<?>> Set<C>	getTerms(Class<C> cls)	Processes the set containing all terms of type C.
Term<?>	getWeight()	Return the weight of this constraint.
int	hashCode()
boolean	isConstraint()	isConstraint
boolean	isEmpty()	return true if the rule's head and body are both empty, false otherwise.
boolean	isFact()	isFact
boolean	isGround()	Checks whether this formula is ground, i.e.
boolean	isLiteral()
boolean	isOptimizationStatement()	Return true if isOptimizationStatement
Boolean	isSafe()	This method tests a rule for safety.
String	printToClingo()	Returns a representation of this ASP element in clingo (potassco) syntax.
String	printToDLV()	Returns a representation of this ASP element in DLV syntax.
void	setBody(ASPBodyElement... aspBodyElements)	Set this rule's body to the given ASPBodyElements.
void	setConclusion(ASPHead conclusion)	Set the conclusion of this rule.
void	setConclusion(ASPLiteral head)	Set the conclusion of this rule.
void	setConstraintTerms(List<Term<?>> constraintTerms)	Setter
void	setHead(ASPHead head)	Set the head of this rule.
void	setHead(ASPLiteral head)	Set the head of this rule.
void	setLevel(Term<?> level)	Set the level attribute of this constraint.
void	setWeight(Term<?> weight)	Set the weight attribute of this constraint.
ASPRule	substitute(Term<?> v, Term<?> t)	Substitutes all occurrences of term "v" in this formula by term "t" and returns the new formula.
String	toString()

Methods inherited from class org.tweetyproject.lp.asp.syntax.ASPElement

containsTermsOfType, getPredicateCls, isWellFormed, substitute

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Details

ASPRule

public ASPRule()

Empty constructor

ASPRule

public ASPRule(ASPHead head)

Creates a fact with the given ASPHead.

Parameters:

head - an ASPHead

ASPRule

public ASPRule(ASPLiteral literal)

Creates a fact with the given literal.

Parameters:

literal - a literal

ASPRule

public ASPRule(ASPHead head,
 List<ASPBodyElement> body)

Creates a rule with the given head and body.

Parameters:

head - an ASPHead

body - a list of ASPBodyElement

ASPRule

public ASPRule(ASPLiteral head,
 ASPBodyElement b)

Creates a rule with the given head and a single-element body.

Parameters:

head - an ASPLiteral

b - a body element

ASPRule

public ASPRule(ASPHead head,
 ASPBodyElement b)

Creates a rule with the given head and a single-element body.

Parameters:

head - an ASPHead

b - a body element

ASPRule

public ASPRule(ASPLiteral head,
 List<ASPBodyElement> body)

Creates a rule with the given head and body.

Parameters:

head - an ASPLiteral

body - a list of ASPBodyElement

ASPRule

public ASPRule(List<ASPBodyElement> body)

Creates a constraint with the given body.

Parameters:

body - a list of ASPBodyElement

ASPRule

public ASPRule(List<ASPBodyElement> nafliterals,
 Term<?> weight,
 List<Term<?>> terms)

Creates a weak constraint with the given weight and terms.

Parameters:

nafliterals - the naf literals

weight - some weight

terms - a list of terms

ASPRule

public ASPRule(List<ASPBodyElement> body,
 Term<?> weight,
 Term<?> level,
 List<Term<?>> terms)

Creates a weak constraint with the given weight, level (priority) and terms.

Parameters:

body - a list of ASPBodyElement

weight - a term

level - a term

terms - a list of terms

ASPRule

public ASPRule(OptimizationStatement opt)

Creates a new rule with the given optimization statement.

Parameters:

opt - OptimizationStatement

ASPRule

public ASPRule(ASPRule other)

Copy-Constructor

Parameters:

other - another ASPRule

Method Details

setConstraintTerms

public void setConstraintTerms(List<Term<?>> constraintTerms)

Setter

Parameters:

constraintTerms - terms

addPremise

public void addPremise(ASPBodyElement premise)

Description copied from interface: Rule

Add the given premise to this rule.

Specified by:

addPremise in interface Rule<ASPHead,ASPBodyElement>

Parameters:

premise - some formula

getPremise

public List<ASPBodyElement> getPremise()

Description copied from interface: Rule

Returns the premise of this rule.

Specified by:

getPremise in interface Rule<ASPHead,ASPBodyElement>

Returns:

the premise of this rule.

addPremises

public void addPremises(Collection<? extends ASPBodyElement> premises)

Description copied from interface: Rule

Add the given premises to this rule.

Specified by:

addPremises in interface Rule<ASPHead,ASPBodyElement>

Parameters:

premises - some formulas

addBody

public void addBody(ASPBodyElement premise)

Add the given body element to this rule.

Parameters:

premise - the premise

getBody

public List<ASPBodyElement> getBody()

Return the body of this rule

Returns:

the body of this rule

addBodyElements

public void addBodyElements(Collection<? extends ASPBodyElement> premises)

Add the given body elements to this rule.

Parameters:

premises - premise

setBody

public void setBody(ASPBodyElement... aspBodyElements)

Set this rule's body to the given ASPBodyElements.

Parameters:

aspBodyElements - the body elements

setConclusion

public void setConclusion(ASPHead conclusion)

Description copied from interface: Rule

Set the conclusion of this rule.

Specified by:

setConclusion in interface Rule<ASPHead,ASPBodyElement>

Parameters:

conclusion - some formula

setConclusion

public void setConclusion(ASPLiteral head)

Set the conclusion of this rule.

Parameters:

head - the head

getConclusion

public ASPHead getConclusion()

Description copied from interface: Rule

Returns the conclusion of this rule.

Specified by:

getConclusion in interface Rule<ASPHead,ASPBodyElement>

Returns:

the conclusion of this rule.

addToHead

public void addToHead(ASPLiteral literal)

Add the given literal to the head of the rule.

Parameters:

literal - ASPLiteral

getHead

public ASPHead getHead()

Return head of this rule

Returns:

head of this rule

setHead

public void setHead(ASPHead head)

Set the head of this rule.

Parameters:

head - the heas

setHead

public void setHead(ASPLiteral head)

Set the head of this rule.

Parameters:

head - the head

getWeight

public Term<?> getWeight()

Return the weight of this constraint.

Returns:

the weight of this constraint.

setWeight

public void setWeight(Term<?> weight)

Set the weight attribute of this constraint.

Parameters:

weight - a term

getLevel

public Term<?> getLevel()

Return the level attribute of this constraint.

Returns:

the level attribute of this constraint.

setLevel

public void setLevel(Term<?> level)

Set the level attribute of this constraint.

Parameters:

level - a term

getConstraintTerms

public List<Term<?>> getConstraintTerms()

Return the constraint terms of this rule.

Returns:

the constraint terms of this rule.

isFact

public boolean isFact()

Description copied from interface: Rule

isFact

Specified by:

isFact in interface Rule<ASPHead,ASPBodyElement>

Returns:

whether the rule is a fact

isConstraint

public boolean isConstraint()

Description copied from interface: Rule

isConstraint

Specified by:

isConstraint in interface Rule<ASPHead,ASPBodyElement>

Returns:

whether the rule is a constraint

isOptimizationStatement

public boolean isOptimizationStatement()

Return true if isOptimizationStatement

Returns:

true if isOptimizationStatement

isEmpty

public boolean isEmpty()

return true if the rule's head and body are both empty, false otherwise.

Returns:

true if the rule's head and body are both empty, false otherwise.

isSafe

public Boolean isSafe()

This method tests a rule for safety. Solvers (such as clingo) usually do not accept unsafe rules. A rule is safe if all of its variables occur in a positive literal (classical atom) in the body of the rule, or as part of one side u of a comparative atom u = t if all variables in t are safe (analogously for switched u and t). A more detailed description can be found in the ASP-2-Core standard description.

Returns:

true if the rule is safe, false otherwise

isGround

public boolean isGround()

Description copied from interface: ComplexLogicalFormula

Checks whether this formula is ground, i.e. whether there appears no variable in this formula.

Specified by:

isGround in interface ComplexLogicalFormula

Overrides:

isGround in class ASPElement

Returns:

"true" if this formula is ground.

getSignature

public FolSignature getSignature()

Description copied from interface: Formula

Returns the signature of the language of this formula.

Specified by:

getSignature in interface Formula

Specified by:

getSignature in interface Rule<ASPHead,ASPBodyElement>

Specified by:

getSignature in class ASPElement

Returns:

the signature of the language of this formula.

isLiteral

public boolean isLiteral()

Specified by:

isLiteral in interface SimpleLogicalFormula

Returns:

true if the formula represents a literal in the language or false otherwise

getTerms

public Set<Term<?>> getTerms()

Specified by:

getTerms in interface LogicStructure

Returns:

a set containing all terms of this logical structure

getTerms

public <C extends Term<?>> Set<C> getTerms(Class<C> cls)

Description copied from interface: LogicStructure

Processes the set containing all terms of type C. This method uses the equals method of the given Class and therefore does not add terms which are sub classes of type C to the set.

Specified by:

getTerms in interface LogicStructure

Type Parameters:

C - the type of terms

Parameters:

cls - The Class structure containing type information about the searched term

Returns:

A set containing all terms of type C of this logical structure

getPredicates

public Set<Predicate> getPredicates()

Description copied from interface: SimpleLogicalFormula

Processes the set of all predicates which appear in this formula

Specified by:

getPredicates in interface SimpleLogicalFormula

Specified by:

getPredicates in class ASPElement

Returns:

all predicates that appear in this formula

getAtoms

public Set<ASPAtom> getAtoms()

Description copied from interface: SimpleLogicalFormula

Processes the set of all atoms which appear in this formula

Specified by:

getAtoms in interface SimpleLogicalFormula

Specified by:

getAtoms in class ASPElement

Returns:

The set of all atoms

getLiterals

public Collection<? extends ASPLiteral> getLiterals()

Retrieves all the literals contained within this rule.

This method gathers and returns a collection of literals that are present in both the head and the body of the rule. The literals are stored in a sorted set, ensuring that they are returned in a consistent order.

Returns:

A sorted collection of literals (ASPLiteral) contained in the head and body of the rule. The returned collection is a SortedSet to maintain a consistent order.

substitute

public ASPRule substitute(Term<?> v,
 Term<?> t)

Description copied from interface: ComplexLogicalFormula

Substitutes all occurrences of term "v" in this formula by term "t" and returns the new formula.

Specified by:

substitute in interface ComplexLogicalFormula

Specified by:

substitute in class ASPElement

Parameters:

v - the term to be substituted.

t - the term to substitute.

Returns:

a formula where every occurrence of "v" is replaced by "t".

exchange

public ASPRule exchange(Term<?> v,
 Term<?> t)

Description copied from interface: ComplexLogicalFormula

Substitutes all occurrences of term "v" in this formula by term "t" and at the same time replaces all occurrences of term "t" by term "v" and eventually returns the new formula.

Specified by:

exchange in interface ComplexLogicalFormula

Overrides:

exchange in class ASPElement

Parameters:

v - a term.

t - a term.

Returns:

a new logical formula with both "v" and "t" exchanged.

compareTo

public int compareTo(ASPRule arg0)

Specified by:

compareTo in interface Comparable<ASPRule>

clone

public ASPRule clone()

Description copied from interface: SimpleLogicalFormula

Creates a deep copy of this formula

Specified by:

clone in interface ComplexLogicalFormula

Specified by:

clone in interface SimpleLogicalFormula

Specified by:

clone in class ASPElement

Returns:

the cloned formula

toString

public String toString()

Overrides:

toString in class Object

printToClingo

public String printToClingo()

Description copied from class: ASPElement

Returns a representation of this ASP element in clingo (potassco) syntax. See https://potassco.org/ for more information.

Overrides:

printToClingo in class ASPElement

Returns:

String representation in clingo syntax

printToDLV

public String printToDLV()

Description copied from class: ASPElement

Returns a representation of this ASP element in DLV syntax. See http://www.dlvsystem.com/html/DLV_User_Manual.html for more information.

Overrides:

printToDLV in class ASPElement

Returns:

String representation in DLV syntax

hashCode

public int hashCode()

Specified by:

hashCode in interface SimpleLogicalFormula

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Specified by:

equals in interface SimpleLogicalFormula

Overrides:

equals in class Object