Package net.sf.tweety.lp.asp.syntax

Class Program

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractSet<E>

java.util.HashSet<T>

net.sf.tweety.commons.util.rules.RuleSet<ASPRule>

net.sf.tweety.lp.asp.syntax.Program

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.lang.Iterable<ASPRule>, java.util.Collection<ASPRule>, java.util.Set<ASPRule>, BeliefBase, LogicProgram<ASPHead,ASPBodyElement,ASPRule>

public class Program
extends RuleSet<ASPRule>
implements LogicProgram<ASPHead,ASPBodyElement,ASPRule>

This class models an ASP-Core-2 program, meaning a set of rules and optionally a query. A program is ground if it contains no variables. The rules are ordered alphabetically.

Author:

Tim Janus, Thomas Vengels, Anna Gessler

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private java.util.Set<Predicate>	output_predicate_whitelist	Optional field that can be used by some solvers.
private ASPLiteral	query	A single query.
private java.util.Set<ASPRule>	rules	The rules of the programs, including facts (rules with no body) and weak constraint (rules with no head).
private static long	serialVersionUID

Constructor Summary

Constructors

Constructor	Description
Program()	Creates a new empty program.
Program(java.util.Collection<ASPRule> rules)	Creates a new program with the given rules.
Program(ASPLiteral query, java.util.Set<ASPRule> rules)	Creates a new program with the given query and rules.
Program(Program other)	Copy-Constructor

Method Summary

Modifier and Type	Method	Description
void	add(Program other)	Adds another program's content to the content of this program.
void	addAll(java.util.List<ASPRule> rules)
void	addFact(ASPHead fact)	Adds the given fact to the program
void	addFact(ASPLiteral fact)
Program	clone()
boolean	contains(ASPRule r)	Returns true if the program contains a given rule.
static Program	defaultification(Program p)	Creates the defaultification p_d of a given program p.
Program	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.
FolSignature	getMinimalSignature()	Returns the signature of the language of this knowledge base.
java.util.Set<Predicate>	getOutputWhitelist()	Returns the whitelist of predicates.
private java.util.Set<Predicate>	getPredicates()	Processes the set of all predicates which appear in this program.
ASPLiteral	getQuery()	Returns the query of the program, if there is one.
java.util.Set<ASPRule>	getRules()	Returns all rules of the program.
boolean	hasQuery()	Returns true if the program contains a query.
boolean	isExtendedProgram()	Checks if the program is an extended program, meaning the heads of the literals do not have more than one literal.
boolean	isGround()
boolean	isSafe()	Returns true if the program is safe, i.e.
Program	reduct(java.util.Set<ASPLiteral> state)	Returns the reduct of this program wrt.
void	setOutputWhitelist(java.util.Collection<Predicate> ps)	Sets the whitelist of predicates.
void	setQuery(ASPLiteral query)	Sets the query of the program.
Program	substitute(java.util.Map<? extends Term<?>,? extends Term<?>> map)	Substitutes all occurrences of all terms "v" in map.keyset() in this formula by map.get(v) and returns the new formula.
Program	substitute(Term<?> v, Term<?> t)	Substitutes all occurrences of term "v" in this formula by term "t" and returns the new formula.
java.lang.String	toString()

Methods inherited from class net.sf.tweety.commons.util.rules.RuleSet

getConclusions, getPremises, getRulesWithConclusion, getSyntacticModule

Methods inherited from class java.util.HashSet

add, clear, contains, isEmpty, iterator, remove, size, spliterator

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

addAll, containsAll, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.Set

addAll, containsAll, equals, hashCode, removeAll, retainAll, toArray, toArray

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

rules

private java.util.Set<ASPRule> rules

The rules of the programs, including facts (rules with no body) and weak constraint (rules with no head).

query

private ASPLiteral query

A single query.

output_predicate_whitelist

private java.util.Set<Predicate> output_predicate_whitelist

Optional field that can be used by some solvers. If used, all atoms will be hidden from the output of the solver except for those with whitelisted predicates. This corresponds to the #show statement of the clingo input language.

Constructor Detail

Program

public Program()

Creates a new empty program.

Program

public Program(java.util.Collection<ASPRule> rules)

Creates a new program with the given rules.

Parameters:

rules - a set of rules

Program

public Program(ASPLiteral query,
               java.util.Set<ASPRule> rules)

Creates a new program with the given query and rules.

Parameters:

query - a query

rules - a set of rules

Program

public Program(Program other)

Copy-Constructor

Parameters:

other - another program

Method Detail

setQuery

public void setQuery(ASPLiteral query)

Sets the query of the program.

Parameters:

query - a literal

addFact

public void addFact(ASPHead fact)

Description copied from interface: LogicProgram

Adds the given fact to the program

Specified by:

addFact in interface LogicProgram<ASPHead,ASPBodyElement,ASPRule>

Parameters:

fact - a fact

getMinimalSignature

public FolSignature getMinimalSignature()

Description copied from interface: BeliefBase

Returns the signature of the language of this knowledge base.

Specified by:

getMinimalSignature in interface BeliefBase

Specified by:

getMinimalSignature in interface LogicProgram<ASPHead,ASPBodyElement,ASPRule>

Returns:

the signature of the language of this knowledge base.

substitute

public Program substitute(Term<?> v,
                          Term<?> t)
                   throws java.lang.IllegalArgumentException

Description copied from interface: LogicProgram

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

Specified by:

substitute in interface LogicProgram<ASPHead,ASPBodyElement,ASPRule>

Parameters:

v - the term to be substituted.

t - the term to substitute.

Returns:

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

Throws:

java.lang.IllegalArgumentException - if "v" and "t" are of different sorts

substitute

public Program substitute(java.util.Map<? extends Term<?>,? extends Term<?>> map)
                   throws java.lang.IllegalArgumentException

Description copied from interface: LogicProgram

Substitutes all occurrences of all terms "v" in map.keyset() in this formula by map.get(v) and returns the new formula.

Specified by:

substitute in interface LogicProgram<ASPHead,ASPBodyElement,ASPRule>

Parameters:

map - a mapping defining which terms to be substituted.

Returns:

a formula where every term in map.keyset() has been replaced by map.get(v).

Throws:

java.lang.IllegalArgumentException - if any term and its mapping are of different sorts

exchange

public Program exchange(Term<?> v,
                        Term<?> t)
                 throws java.lang.IllegalArgumentException

Description copied from interface: LogicProgram

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 LogicProgram<ASPHead,ASPBodyElement,ASPRule>

Parameters:

v - a term.

t - a term.

Returns:

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

Throws:

java.lang.IllegalArgumentException - if "v" and "t" are of different sorts

toString

public java.lang.String toString()

Specified by:

toString in interface BeliefBase

Specified by:

toString in interface LogicProgram<ASPHead,ASPBodyElement,ASPRule>

Overrides:

toString in class java.util.AbstractCollection<ASPRule>

isGround

public boolean isGround()

clone

public Program clone()

Overrides:

clone in class java.util.HashSet<ASPRule>

setOutputWhitelist

public void setOutputWhitelist(java.util.Collection<Predicate> ps)

Sets the whitelist of predicates. Solvers that use this option will only show atoms over predicates in this set in their output.

Parameters:

ps - set of predicates

getOutputWhitelist

public java.util.Set<Predicate> getOutputWhitelist()

Returns the whitelist of predicates. Solvers that use this option will only show atoms over predicates in this set in their output.

Returns:

set of whitelisted predicates

getPredicates

private java.util.Set<Predicate> getPredicates()

Processes the set of all predicates which appear in this program.

Returns:

set of predicates

hasQuery

public boolean hasQuery()

Returns true if the program contains a query.

Returns:

true if the program has a query, false otherwise

getQuery

public ASPLiteral getQuery()

Returns the query of the program, if there is one.

Returns:

a literal, or null if the program has no query

getRules

public java.util.Set<ASPRule> getRules()

Returns all rules of the program.

Returns:

set of rules

reduct

public Program reduct(java.util.Set<ASPLiteral> state)

Returns the reduct of this program wrt. the given state, i.e. a program that contains no default negation and only those rules of this program (without all default-negated literals in the body) that do not have a default-negated version of a literal in their body.

Parameters:

state - some set of literals

Returns:

the reduct of this program

defaultification

public static Program defaultification(Program p)

Creates the defaultification p_d of a given program p. A defaultificated program p' of p adds for every Rule r in p a modified rule r_d of the form: 'H(r) :- B(r), not -H(r).' to the program p'.

Parameters:

p - The program which is not defaultificated yet

Returns:

a program p' which is the defaultificated version of p.

addFact

public void addFact(ASPLiteral fact)

isExtendedProgram

public boolean isExtendedProgram()

Checks if the program is an extended program, meaning the heads of the literals do not have more than one literal.

Returns:

True if the program is an extended program, false otherwise.

add

public void add(Program other)

Adds another program's content to the content of this program.

Parameters:

other - Reference to the other program.

addAll

public void addAll(java.util.List<ASPRule> rules)

contains

public boolean contains(ASPRule r)

Returns true if the program contains a given rule.

Parameters:

r - an ASP rule

Returns:

true if program contains r

isSafe

public boolean isSafe()

Returns true if the program is safe, i.e. if all of its rules and its query are safe.

Returns:

true if the program is safe, false otherwise