tuffy.mln
Class Literal

java.lang.Object
  tuffy.mln.Literal

All Implemented Interfaces:

java.lang.Cloneable

public class Literal
extends java.lang.Object
implements java.lang.Cloneable

A literal in first-order logic.

Nested Class Summary

private class

Literal.VarClique Clique of variables.

Field Summary

private boolean	coversAllMaterializedTuples
private int	idx The index of this literal in its parent clause.
private Predicate	pred Predicate object associated with this literal.
private boolean	sense The positive/negative value of this literal.
private java.util.ArrayList<Term>	terms List of terms (variable/constant) contained in this literal.
private Tuple	tuple The tuple format of this literal.
private java.util.HashSet<java.lang.String>	vars The name set of all variables in this literal.

Constructor Summary

Literal(Predicate predicate, boolean sense)
Constructor of Literal.

Method Summary

void	appendTerm(Term t) Append a new term to this literal.
java.lang.Object	clone()
boolean	coversAllMaterializedTuples() Test whether we want this literal to cover all materialized tuples regardless of the sense of this literal.
void	flipSense() Flip the sense of this literal.
int	getIdx() Return the assigned index of this literal in its parent clause.
Predicate	getPred() Return the predicate of this literal.
boolean	getSense() Return true if this is a positive literal.
java.util.ArrayList<Term>	getTerms() Return the list of terms in this literal.
java.util.HashSet<java.lang.String>	getVars() Return the set of variable names in this literal.
boolean	isBuiltIn() Return whether the predicate of this literal is a built-in predicate.
boolean	isSameAs(Literal lit) Compare a given literal with this one.
java.util.HashMap<java.lang.String,Term>	mostGeneralUnification(Tuple atuple) Compute the most general unification (MGU) of two literals.
void	setCoversAllMaterializedTuples(boolean coversAllMaterializedTuples) Set whether we want this literal to cover all materialized tuples regardless of the sense of this literal.
void	setIdx(int i) Assign an unique (within its parent clause) index to this literal.
void	setSense(boolean asense) Set the sense of this literal.
Literal	substitute(java.util.HashMap<java.lang.String,Term> vmap) Apply a substitution to this literal.
Atom	toAtom(Atom.AtomType type) Convert this literal to an atom.
java.lang.String	toString() Return the human-friendly representation of this literal.
Tuple	toTuple() Convert this literal into a tuple.

Methods inherited from class java.lang.Object

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

Field Detail

pred

private Predicate pred

Predicate object associated with this literal.

idx

private int idx

The index of this literal in its parent clause.

terms

private java.util.ArrayList<Term> terms

List of terms (variable/constant) contained in this literal.

sense

private boolean sense

The positive/negative value of this literal. Here the positive/negative refers to that in Horn clause.

coversAllMaterializedTuples

private boolean coversAllMaterializedTuples

tuple

private Tuple tuple

The tuple format of this literal. Need call toTuple() to make this variable not null. This variable is not automatically maintained. To obtain the most update to date version, you need to call toTuple().

vars

private java.util.HashSet<java.lang.String> vars

The name set of all variables in this literal.

Constructor Detail

Literal

public Literal(Predicate predicate,
               boolean sense)

Constructor of Literal.

Parameters:

predicate - the predicate

sense - true for a positive literal; false for a negative one

Method Detail

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Overrides:

clone in class java.lang.Object

Throws:

java.lang.CloneNotSupportedException

isBuiltIn

public boolean isBuiltIn()

Return whether the predicate of this literal is a built-in predicate.

getVars

public java.util.HashSet<java.lang.String> getVars()

Return the set of variable names in this literal.

getPred

public Predicate getPred()

Return the predicate of this literal.

getTerms

public java.util.ArrayList<Term> getTerms()

Return the list of terms in this literal.

getIdx

public int getIdx()

Return the assigned index of this literal in its parent clause.

setIdx

public void setIdx(int i)

Assign an unique (within its parent clause) index to this literal.

Parameters:

i - the index

See Also:

Clause.addLiteral(Literal)

mostGeneralUnification

public java.util.HashMap<java.lang.String,Term> mostGeneralUnification(Tuple atuple)

Compute the most general unification (MGU) of two literals.

Parameters:

atuple - the literal (in the form of a tuple) to be unified

Returns:

the MGU in the form of a mapping from variables to variables/constants

toString

public java.lang.String toString()

Return the human-friendly representation of this literal.

Overrides:

toString in class java.lang.Object

appendTerm

public void appendTerm(Term t)

Append a new term to this literal.

Parameters:

t - the term to be appended

toTuple

public Tuple toTuple()

Convert this literal into a tuple. This will assign an internal ID for variables obeying the syntax of class Tuple from Strings.

isSameAs

public boolean isSameAs(Literal lit)

Compare a given literal with this one. By ``same'', it means 1) predicate is same; 2) sense is same; 3) corresponding constant is same; and 4) the name of corresponding variable is same. (Do not consider substitution).

Parameters:

lit - the literal needed to be compared.

Returns:

true if these two literals are the same, false otherwise.

substitute

public Literal substitute(java.util.HashMap<java.lang.String,Term> vmap)

Apply a substitution to this literal.

Parameters:

vmap - the substitution

Returns:

the new literal

toAtom

public Atom toAtom(Atom.AtomType type)

Convert this literal to an atom.

Parameters:

type - indicates if it's an evidence, a query, etc.

flipSense

public void flipSense()

Flip the sense of this literal.

getSense

public boolean getSense()

Return true if this is a positive literal. Here the positive/negative refers to that in Horn clause.

setSense

public void setSense(boolean asense)

Set the sense of this literal.

Parameters:

asense - true if this is intended to be a positive literal

setCoversAllMaterializedTuples

public void setCoversAllMaterializedTuples(boolean coversAllMaterializedTuples)

Set whether we want this literal to cover all materialized tuples regardless of the sense of this literal.

Parameters:

coversAllMaterializedTuples -

coversAllMaterializedTuples

public boolean coversAllMaterializedTuples()

Test whether we want this literal to cover all materialized tuples regardless of the sense of this literal.