repthy
Class HashGroup

Object
  AbstractCollection
      AbstractSet
          ImmutableSet
              Group
                  HashGroup

All Implemented Interfaces:

Collection, Set

Direct Known Subclasses:

AbelianGroup, GL, PermGp, PGL, PGroup, ProductGroup, PSL, QuotientGroup, SL

public class HashGroup

extends Group

An implementation of Group backed by a HashSet that holds one copy of each element of the group.

Author:

Mark McConnell

Field Summary

Fields inherited from class Group

charTable

Constructor Summary

HashGroup(GroupElt[] generators)
Constructs the group with the given generators.

HashGroup(Set set)
set is a Set holding GroupElts.

Method Summary

boolean	contains(Object g)
Set	getConjClass(int i) Returns the i-th conjugacy class as an unmodifiable Set.
int	getConjClassIndex(GroupElt g) Returns i such that g is in the i-th conjugacy class.
int	getConjClassNum() Returns the number of conjugacy classes.
Iterator	iterator() Returns an iterator over the elements of the group.
int	size()

Methods inherited from class Group

cyclicSubgpsUpToConj, describeOrder8, elementarySubgps, fillInCharTable, getCenter, getCentralizer, getCharComparator, getCharTable, getCommutatorSubgroup, getCompositionSeries, getConjClassRep, getEltOrder, getEltOrder, getIdentity, getOrder, getProperNormalSubgroup, getSylow, isAbelian, isCentral, isSimple, isSubgroupOf, order, power, printTest, tableTest

Methods inherited from class ImmutableSet

add, addAll, clear, remove, removeAll, retainAll

Methods inherited from class AbstractSet

equals, hashCode

Methods inherited from class AbstractCollection

containsAll, isEmpty, toArray, toArray, toString

Methods inherited from class Object

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

Methods inherited from interface Set

containsAll, isEmpty, toArray, toArray

Constructor Detail

HashGroup

public HashGroup(Set set)

set is a Set holding GroupElts. It must be non-empty, and the elements must satisfy the group axioms. There is no error-checking, but expect trouble if these conditions are not met. set is copied, so that changes to it later will not affect what's inside this group.

HashGroup

public HashGroup(GroupElt[] generators)

Constructs the group with the given generators. The algorithm walks naively through the Cayley graph on the generators, hence has running time depending on the number of edges in the Cayley graph times its diameter. The group is backed by a HashSet holding one copy of every element.

Throws:

IllegalArgumentException - If generators does not have at least one element.

Method Detail

contains

public boolean contains(Object g)

iterator

public Iterator iterator()

Returns an iterator over the elements of the group. The elements appear in an unspecified order.

Throws:

UnsupportedOperationException - if you call remove() on this iterator.

size

public int size()

getConjClassNum

public int getConjClassNum()

Description copied from class: Group

Returns the number of conjugacy classes.

Specified by:

getConjClassNum in class Group

getConjClass

public Set getConjClass(int i)

Returns the i-th conjugacy class as an unmodifiable Set. The inverse operation is getConjClassIndex(repthy.GroupElt). If an element of the class implements Comparable, then the corresponding Set will be a SortedSet.

Specified by:

getConjClass in class Group

Throws:

ArrayIndexOutOfBoundsException - unless 0 ≤ i < getConjClassNum().

getConjClassIndex

public int getConjClassIndex(GroupElt g)

Returns i such that g is in the i-th conjugacy class. The inverse operation is getConjClass(int).

Specified by:

getConjClassIndex in class Group

Throws:

NullPointerException - if g is not in the group.