net.sf.tweety.logics.pl.util

Class CanonicalIterator

java.lang.Object

net.sf.tweety.logics.pl.util.CanonicalIterator

All Implemented Interfaces:

java.util.Iterator<PlBeliefSet>, BeliefSetIterator<PropositionalFormula,PlBeliefSet>

public class CanonicalIterator
extends java.lang.Object
implements BeliefSetIterator<PropositionalFormula,PlBeliefSet>

Provides an iterator on all syntactically equivalent knowledge bases.

Author:

Matthias Thimm

Field Summary

Fields

Modifier and Type	Field and Description
private java.math.BigInteger	next The next value used for compiling a knowledge base.
private java.math.BigInteger	upperBoundIndex The upper bound used for enumerating knowledge bases.

Constructor Summary

Constructors

Constructor and Description
CanonicalIterator() Default constructor.
CanonicalIterator(java.math.BigInteger startIndex) Creates a new enumerator that enumerates knowledge bases starting from the given index
CanonicalIterator(java.math.BigInteger startIndex, java.math.BigInteger endIndex) Creates a new enumerator that enumerates knowledge bases starting from the given start index up to the given end index (including)
CanonicalIterator(java.lang.Integer startIndex) Creates a new enumerator that enumerates knowledge bases starting from the given index
CanonicalIterator(java.lang.Integer startIndex, java.lang.Integer endIndex) Creates a new enumerator that enumerates knowledge bases starting from the given start index up to the given end index (including)
CanonicalIterator(java.lang.Long startIndex) Creates a new enumerator that enumerates knowledge bases starting from the given index
CanonicalIterator(java.lang.Long startIndex, java.lang.Long endIndex) Creates a new enumerator that enumerates knowledge bases starting from the given start index up to the given end index (including)

Method Summary

Modifier and Type	Method and Description
static java.util.BitSet	beliefSet2BitSet(PlBeliefSet bs) Creates a bitset representation of the given belief set.
private PlBeliefSet	bitset2BeliefSet(java.util.BitSet s) Parses a knowledge base (PlBeliefSet) from the the given bitset.
private static java.lang.String	formula2String(PropositionalFormula f, java.util.Map<Proposition,java.lang.Integer> prop) Encodes the given formula as a bitstring.
private void	gotoNextValidIndex() Sets this.next to the next value actually encoding a belief base (or to this.upperBoundIndex if set).
boolean	hasNext()
private boolean	isLessThan(java.util.BitSet s, boolean equal, int i, int j, int k, int l) Checks whether the bitvector at positions [i,...,j] is less than the bitvector at positions [k,...,l].
PlBeliefSet	next()
java.math.BigInteger	nextIndex() Returns the index of the next element.
private Pair<java.util.Collection<PropositionalFormula>,java.lang.Integer>	parseAssociativeFormula(java.util.BitSet s, int idx, int numOfTerms, PropositionalSignature sig) Parses an associate formula from the given bitset starting at index idx, with the given number of terms and the given signature
private Pair<PropositionalFormula,java.lang.Integer>	parseFormula(java.util.BitSet s, int idx, PropositionalSignature sig) Reads the next formula of the given bitset, starting at the given index.
private Pair<PropositionalFormula,java.lang.Integer>	parseProposition(java.util.BitSet s, int idx, PropositionalSignature sig) Parses a proposition in bitset s starting from idx.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Field Detail

upperBoundIndex

private java.math.BigInteger upperBoundIndex

The upper bound used for enumerating knowledge bases.

next

private java.math.BigInteger next

The next value used for compiling a knowledge base.

Constructor Detail

CanonicalIterator

public CanonicalIterator()

Default constructor. Creates an enumerator that enumerates knowledge bases starting from index 1.

CanonicalIterator

public CanonicalIterator(java.lang.Long startIndex)

Creates a new enumerator that enumerates knowledge bases starting from the given index

Parameters:

startIndex - some integer value

CanonicalIterator

public CanonicalIterator(java.lang.Integer startIndex)

Creates a new enumerator that enumerates knowledge bases starting from the given index

Parameters:

startIndex - some integer value

CanonicalIterator

public CanonicalIterator(java.math.BigInteger startIndex)

Creates a new enumerator that enumerates knowledge bases starting from the given index

Parameters:

startIndex - some integer value

CanonicalIterator

public CanonicalIterator(java.lang.Long startIndex,
                         java.lang.Long endIndex)

Creates a new enumerator that enumerates knowledge bases starting from the given start index up to the given end index (including)

Parameters:

startIndex - some integer value

endIndex - some integer value

CanonicalIterator

public CanonicalIterator(java.lang.Integer startIndex,
                         java.lang.Integer endIndex)

Creates a new enumerator that enumerates knowledge bases starting from the given start index up to the given end index (including)

Parameters:

startIndex - some integer value

endIndex - some integer value

CanonicalIterator

public CanonicalIterator(java.math.BigInteger startIndex,
                         java.math.BigInteger endIndex)

Creates a new enumerator that enumerates knowledge bases starting from the given start index up to the given end index (including)

Parameters:

startIndex - some integer value

endIndex - some integer value

Method Detail

gotoNextValidIndex

private void gotoNextValidIndex()

Sets this.next to the next value actually encoding a belief base (or to this.upperBoundIndex if set).

isLessThan

private boolean isLessThan(java.util.BitSet s,
                           boolean equal,
                           int i,
                           int j,
                           int k,
                           int l)

Checks whether the bitvector at positions [i,...,j] is less than the bitvector at positions [k,...,l]. If equal=true, "less" is substituted by "less or equal".

Parameters:

s - some bitset

equal - whether equality is allowed

i - start index of first bitvector (including)

j - end index of first bitvector (including)

k - start index of second bitvector (including)

l - end index of second bitvector (including)

Returns:

"true" if [i,...,j] is less (or equal) [k,...,l]

parseAssociativeFormula

private Pair<java.util.Collection<PropositionalFormula>,java.lang.Integer> parseAssociativeFormula(java.util.BitSet s,
                                                                                                   int idx,
                                                                                                   int numOfTerms,
                                                                                                   PropositionalSignature sig)

Parses an associate formula from the given bitset starting at index idx, with the given number of terms and the given signature

Parameters:

s - some bitset

idx - the starting index of the formula to be parsed

numOfTerms - the number of terms to be parsed

sig - the current signature

Returns:

the set of parsed terms and the index position in s after this formula

parseProposition

private Pair<PropositionalFormula,java.lang.Integer> parseProposition(java.util.BitSet s,
                                                                      int idx,
                                                                      PropositionalSignature sig)

Parses a proposition in bitset s starting from idx.

Parameters:

s - some bitset

idx - the starting index of the proposition

sig - the current signature

Returns:

the formula parsed and the index in s after this formula

parseFormula

private Pair<PropositionalFormula,java.lang.Integer> parseFormula(java.util.BitSet s,
                                                                  int idx,
                                                                  PropositionalSignature sig)

Reads the next formula of the given bitset, starting at the given index.

Parameters:

b - a bitset

idx - the start index of a formula

sig - the current signature

Returns:

the formula that has been read and the index right in the bitset right after this formula; if the bitset if invalid, "null" is returned

bitset2BeliefSet

private PlBeliefSet bitset2BeliefSet(java.util.BitSet s)

Parses a knowledge base (PlBeliefSet) from the the given bitset. If the bitset does not encode a PlBeliefSet, null is returned

Parameters:

s - some bitset

Returns:

the knowledge base encoded by the bitset, or null.

hasNext

public boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator<PlBeliefSet>

Specified by:

hasNext in interface BeliefSetIterator<PropositionalFormula,PlBeliefSet>

next

public PlBeliefSet next()

Specified by:

next in interface java.util.Iterator<PlBeliefSet>

Specified by:

next in interface BeliefSetIterator<PropositionalFormula,PlBeliefSet>

nextIndex

public java.math.BigInteger nextIndex()

Returns the index of the next element.

Returns:

the index of the next element.

formula2String

private static java.lang.String formula2String(PropositionalFormula f,
                                               java.util.Map<Proposition,java.lang.Integer> prop)

Encodes the given formula as a bitstring.

Parameters:

f - some formula

prop - map of propositions to their indices

Returns:

a bitstring representing the formula

beliefSet2BitSet

public static java.util.BitSet beliefSet2BitSet(PlBeliefSet bs)

Creates a bitset representation of the given belief set.

Parameters:

bs - some belief set

Returns:

a bitset representation of the belief set