edu.illinois.cs.cogcomp.lbjava.infer

Class PropositionalConjunction

java.lang.Object

edu.illinois.cs.cogcomp.lbjava.infer.Constraint

edu.illinois.cs.cogcomp.lbjava.infer.PropositionalConstraint

edu.illinois.cs.cogcomp.lbjava.infer.PropositionalNAryConstraint

edu.illinois.cs.cogcomp.lbjava.infer.PropositionalConjunction

All Implemented Interfaces:

Cloneable

public class PropositionalConjunction
extends PropositionalNAryConstraint

Represents the conjunction of two propositional constraints.

Author:

Nick Rizzolo

Field Summary

Fields inherited from class edu.illinois.cs.cogcomp.lbjava.infer.PropositionalNAryConstraint

children

Constructor Summary

Constructors

Constructor and Description
PropositionalConjunction(PropositionalConstraint c1, PropositionalConstraint c2) If either of the arguments is itself a PropositionalConjunction, its contents are flattened into this PropositionalConjunction.

Method Summary

Modifier and Type	Method and Description
void	add(PropositionalConstraint c) If the given constraint has the same type as this constraint, its terms are merged into this constraint; otherwise, it is added as a new term.
PropositionalConstraint	CNF() Produces a new, logically simplified version of this constraint in conjunctive normal form (CNF).
boolean	containsAll(PropositionalConjunction c) Determines whether this conjunction contains all of the terms that the given conjunction contains.
PropositionalConstraint	distribute(PropositionalDisjunction d) Distributes the given disjunction over this conjunction.
PropositionalConstraint	DNF() Produces a new, logically simplified version of this constraint in disjunctive normal form (DNF).
boolean	equals(Object o) Two PropositionalConjunctions are equivalent when they are topologically equivalent, respecting the associativity and commutivity of conjunction.
boolean	evaluate() Determines whether the constraint is satisfied.
PropositionalConstraint	factor() Factoring a conjunction is the opposite of distributing a disjunction over a conjunction.
int	hashCode() The hash code of a PropositionalConjunction is the sum of the hash codes of its children plus one.
PropositionalConstraint[]	intersect(PropositionalConstraint c) The intersection of two conjunctions is the set of all terms that are common to both conjunctions; the intersection of a conjunction and some other constraint c is c if c is contained in the conjunction and the empty set otherwise.
boolean	moreGeneralThan(PropositionalConstraint c) Compares topology to determine if this constraint is more general than the given constraint; note: this method is not required to be correct when it answers false.
boolean	moreSpecificThan(PropositionalAtLeast c) Compares topology to determine if this constraint is more specific than the given at-least; note: this method is not required to be correct when it answers false.
boolean	moreSpecificThan(PropositionalConjunction c) Compares topology to determine if this constraint is more specific than the given conjunction; note: this method is not required to be correct when it answers false.
boolean	moreSpecificThan(PropositionalConstant c) Compares topology to determine if this constraint is more specific than the given constant; note: this method is not required to be correct when it answers false.
boolean	moreSpecificThan(PropositionalDisjunction c) Compares topology to determine if this constraint is more specific than the given disjunction; note: this method is not required to be correct when it answers false.
boolean	moreSpecificThan(PropositionalDoubleImplication c) Compares topology to determine if this constraint is more specific than the given double implication; note: this method is not required to be correct when it answers false.
boolean	moreSpecificThan(PropositionalImplication c) Compares topology to determine if this constraint is more specific than the given implication; note: this method is not required to be correct when it answers false.
boolean	moreSpecificThan(PropositionalNegation c) Compares topology to determine if this constraint is more specific than the given negation; note: this method is not required to be correct when it answers false.
boolean	moreSpecificThan(PropositionalVariable c) Compares topology to determine if this constraint is more specific than the given variable; note: this method is not required to be correct when it answers false.
PropositionalConstraint	negate() Uses DeMorgan's law to compute the negation of this constraint by distributing that negation to each child.
void	runVisit(Inference infer) Calls the appropriate visit(·) method of the given Inference for this Constraint, as per the visitor pattern.
PropositionalConstraint	simplify() Produces a new, logically simplified version of this constraint, preserving variable consolidation.
PropositionalConstraint	simplify(boolean d) Same as simplify(), except this method gives the caller the ability to optionally leave double implications that are immediate children of this conjunction in tact.
PropositionalConstraint	subtract(PropositionalConstraint[] terms) Subtraction from a conjunction simply removes all of the specified terms from it; this method returns a new constraint representing the subtraction.
void	write(StringBuffer buffer) Creates a string respresentation of this constraint using the string representations of the objects involved.

Methods inherited from class edu.illinois.cs.cogcomp.lbjava.infer.PropositionalNAryConstraint

clone, consolidateVariables, contains, getChildren, size

Methods inherited from class edu.illinois.cs.cogcomp.lbjava.infer.PropositionalConstraint

toString

Methods inherited from class java.lang.Object

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

Constructor Detail

PropositionalConjunction

public PropositionalConjunction(PropositionalConstraint c1,
                                PropositionalConstraint c2)

If either of the arguments is itself a PropositionalConjunction, its contents are flattened into this PropositionalConjunction.

Parameters:

c1 - One constraint to disjunct.

c2 - Another constraint to disjunct.

Method Detail

evaluate

public boolean evaluate()

Determines whether the constraint is satisfied.

Specified by:

evaluate in class Constraint

simplify

public PropositionalConstraint simplify()

Produces a new, logically simplified version of this constraint, preserving variable consolidation.

Specified by:

simplify in class PropositionalConstraint

Returns:

A logically simplified version of this constraint.

See Also:

Constraint.consolidateVariables(java.util.AbstractMap)

simplify

public PropositionalConstraint simplify(boolean d)

Same as simplify(), except this method gives the caller the ability to optionally leave double implications that are immediate children of this conjunction in tact.

Parameters:

d - true iff double implications that are immediate children of this conjunction are to be left in tact.

Returns:

A logically simplified version of this constraint.

negate

public PropositionalConstraint negate()

Uses DeMorgan's law to compute the negation of this constraint by distributing that negation to each child.

Specified by:

negate in class PropositionalConstraint

Returns:

A simplified constraint representing the negation of this constraint.

CNF

public PropositionalConstraint CNF()

Produces a new, logically simplified version of this constraint in conjunctive normal form (CNF).

Specified by:

CNF in class PropositionalConstraint

Returns:

The conjunctive normal form of this constraint.

DNF

public PropositionalConstraint DNF()

Produces a new, logically simplified version of this constraint in disjunctive normal form (DNF).

Specified by:

DNF in class PropositionalConstraint

Returns:

The disjunctive normal form of this constraint.

moreGeneralThan

public boolean moreGeneralThan(PropositionalConstraint c)

Compares topology to determine if this constraint is more general than the given constraint; note: this method is not required to be correct when it answers false.

Specified by:

moreGeneralThan in class PropositionalConstraint

Parameters:

c - The given constraint.

Returns:

true if a topological analysis determined that this constraint is more general than the given constraint.

moreSpecificThan

public boolean moreSpecificThan(PropositionalImplication c)

Compares topology to determine if this constraint is more specific than the given implication; note: this method is not required to be correct when it answers false.

Specified by:

moreSpecificThan in class PropositionalConstraint

Parameters:

c - The given implication.

Returns:

true if a topological analysis determined that this constraint is more specific than the given implication.

moreSpecificThan

public boolean moreSpecificThan(PropositionalDoubleImplication c)

Compares topology to determine if this constraint is more specific than the given double implication; note: this method is not required to be correct when it answers false.

Specified by:

moreSpecificThan in class PropositionalConstraint

Parameters:

c - The given double implication.

Returns:

true if a topological analysis determined that this constraint is more specific than the given double implication.

moreSpecificThan

public boolean moreSpecificThan(PropositionalConjunction c)

Compares topology to determine if this constraint is more specific than the given conjunction; note: this method is not required to be correct when it answers false.

Specified by:

moreSpecificThan in class PropositionalConstraint

Parameters:

c - The given conjunction.

Returns:

true if a topological analysis determined that this constraint is more specific than the given conjunction.

moreSpecificThan

public boolean moreSpecificThan(PropositionalDisjunction c)

Compares topology to determine if this constraint is more specific than the given disjunction; note: this method is not required to be correct when it answers false.

Specified by:

moreSpecificThan in class PropositionalConstraint

Parameters:

c - The given disjunction.

Returns:

true if a topological analysis determined that this constraint is more specific than the given disjunction.

moreSpecificThan

public boolean moreSpecificThan(PropositionalAtLeast c)

Compares topology to determine if this constraint is more specific than the given at-least; note: this method is not required to be correct when it answers false.

Specified by:

moreSpecificThan in class PropositionalConstraint

Parameters:

c - The given at-least.

Returns:

true if a topological analysis determined that this constraint is more specific than the given disjunction.

moreSpecificThan

public boolean moreSpecificThan(PropositionalNegation c)

Compares topology to determine if this constraint is more specific than the given negation; note: this method is not required to be correct when it answers false.

Specified by:

moreSpecificThan in class PropositionalConstraint

Parameters:

c - The given negation.

Returns:

true if a topological analysis determined that this constraint is more specific than the given negation.

moreSpecificThan

public boolean moreSpecificThan(PropositionalVariable c)

Compares topology to determine if this constraint is more specific than the given variable; note: this method is not required to be correct when it answers false.

Specified by:

moreSpecificThan in class PropositionalConstraint

Parameters:

c - The given variable.

Returns:

true if a topological analysis determined that this constraint is more specific than the given variable.

moreSpecificThan

public boolean moreSpecificThan(PropositionalConstant c)

Compares topology to determine if this constraint is more specific than the given constant; note: this method is not required to be correct when it answers false.

Specified by:

moreSpecificThan in class PropositionalConstraint

Parameters:

c - The given constant.

Returns:

true if a topological analysis determined that this constraint is more specific than the given constant.

add

public void add(PropositionalConstraint c)

If the given constraint has the same type as this constraint, its terms are merged into this constraint; otherwise, it is added as a new term.

Parameters:

c - The constraint to add.

factor

public PropositionalConstraint factor()

Factoring a conjunction is the opposite of distributing a disjunction over a conjunction.

Returns:

A constraint that represents a factoring of this conjunction.

intersect

public PropositionalConstraint[] intersect(PropositionalConstraint c)

The intersection of two conjunctions is the set of all terms that are common to both conjunctions; the intersection of a conjunction and some other constraint c is c if c is contained in the conjunction and the empty set otherwise.

Parameters:

c - The constraint to intersect with.

Returns:

The set of common terms in array form or null if there are none.

subtract

public PropositionalConstraint subtract(PropositionalConstraint[] terms)

Subtraction from a conjunction simply removes all of the specified terms from it; this method returns a new constraint representing the subtraction.

Parameters:

terms - The terms to remove.

Returns:

A new representation of this n-ary constraint with the specified terms removed.

distribute

public PropositionalConstraint distribute(PropositionalDisjunction d)

Distributes the given disjunction over this conjunction.

Returns:

A simplified constraint representing the distribution of the given disjunction over this conjunction.

containsAll

public boolean containsAll(PropositionalConjunction c)

Determines whether this conjunction contains all of the terms that the given conjunction contains.

Parameters:

c - The given conjunction.

Returns:

true iff this conjunction contains all of the terms that the given conjunction contains.

hashCode

public int hashCode()

The hash code of a PropositionalConjunction is the sum of the hash codes of its children plus one.

Overrides:

hashCode in class Object

Returns:

The hash code for this PropositionalConjunction.

equals

public boolean equals(Object o)

Two PropositionalConjunctions are equivalent when they are topologically equivalent, respecting the associativity and commutivity of conjunction.

Overrides:

equals in class Object

Returns:

true iff the argument is an equivalent PropositionalConjunction.

runVisit

public void runVisit(Inference infer)

Calls the appropriate visit(·) method of the given Inference for this Constraint, as per the visitor pattern.

Specified by:

runVisit in class Constraint

Parameters:

infer - The inference visiting this constraint.

write

public void write(StringBuffer buffer)

Creates a string respresentation of this constraint using the string representations of the objects involved.

Specified by:

write in class PropositionalConstraint

Parameters:

buffer - The output of this method will be appended to this buffer.