net.sf.tweety.commons.util

Class SetTools<E>

java.lang.Object

net.sf.tweety.commons.util.SetTools<E>

public class SetTools<E>
extends Object

This class provides some methods for set operations.

Author:

Matthias Thimm

Constructor Summary

Constructors

Constructor and Description
SetTools()

Method Summary

Modifier and Type	Method and Description
Set<Set<Set<E>>>	getBipartitions(Set<E> set) Computes every bipartition of the given set, e.g.
Set<E>	getUnion(Set<Set<E>> sets) Returns the union of the set of sets.
boolean	hasEmptyIntersection(Set<Set<E>> sets) Checks whether the given set of sets has an empty intersection
Set<Set<E>>	irreducibleHittingSets(Set<Set<E>> sets) Computes the set of irreducible hitting sets of "sets".
Set<Set<E>>	permutations(Set<Set<E>> partitions) Computes all permutations of elements in partitions as follows.
Set<Set<E>>	subsets(Collection<? extends E> elements) This method computes all subsets of the given set of elements of class "E".
Set<Set<E>>	subsets(Collection<? extends E> elements, int size) This method computes all subsets of the given set of elements of class "E" with the given size.

Methods inherited from class java.lang.Object

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

Constructor Detail

SetTools

public SetTools()

Method Detail

subsets

public Set<Set<E>> subsets(Collection<? extends E> elements)

This method computes all subsets of the given set of elements of class "E".

Parameters:

elements - a set of elements of class "E".

Returns:

all subsets of "elements".

subsets

public Set<Set<E>> subsets(Collection<? extends E> elements,
                           int size)

This method computes all subsets of the given set of elements of class "E" with the given size.

Parameters:

elements - a set of elements of class "E".

size - some int.

Returns:

all subsets of "elements" of the given size.

permutations

public Set<Set<E>> permutations(Set<Set<E>> partitions)

Computes all permutations of elements in partitions as follows. For any set A in the result and any set B in partitions it holds, that exactly one element of B is in A. For example
permutations({{a,b},{c,d,e},{f}})
equals to
{{a,c,f},{b,c,f},{a,d,f},{b,d,f},{a,e,f},{b,e,f}}

Parameters:

partitions - a set of sets of E.

Returns:

a set of sets of E.

irreducibleHittingSets

public Set<Set<E>> irreducibleHittingSets(Set<Set<E>> sets)

Computes the set of irreducible hitting sets of "sets". A hitting set H is a set that has a non-empty intersection with every set in "sets". H is irreducible if no proper subset of H is a hitting set.

Parameters:

sets - a set of sets

Returns:

the set of all irreducible hitting sets of "sets"

hasEmptyIntersection

public boolean hasEmptyIntersection(Set<Set<E>> sets)

Checks whether the given set of sets has an empty intersection

Parameters:

sets - some set of sets

Returns:

true iff the all sets have an empty intersection.

getUnion

public Set<E> getUnion(Set<Set<E>> sets)

Returns the union of the set of sets.

Parameters:

sets - some set of sets

Returns:

the union of the set.

getBipartitions

public Set<Set<Set<E>>> getBipartitions(Set<E> set)

Computes every bipartition of the given set, e.g. for a set {a,b,c,d,e,f} this method returns a set containing for example {{a,b,c,d,e},{f}} and {{a,b,c,},{d,e,f}} and {{a,b,c,d,e,f},{}} and {{a,d,e},{b,c,f}}.

Parameters:

set - a set of E

Returns:

the set of all bipartitions of the given set.