permlib 0.2.9
Library for permutation computations
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symmetric_group_transversal.h
1// ---------------------------------------------------------------------------
2//
3// This file is part of PermLib.
4//
5// Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de>
6// All rights reserved.
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31
32
33#ifndef SYMMETRIC_GROUP_TRANSVERSAL_H_
34#define SYMMETRIC_GROUP_TRANSVERSAL_H_
35
36#include <boost/iterator/counting_iterator.hpp>
37
38namespace permlib {
39
40template<class PERM>
41struct SymmetricGroup;
42
44template<class PERM>
46 public:
48
52 SymmetricGroupTransversal(const SymmetricGroup<PERM>* sg, unsigned int basePos) : symmetricGroup(sg), m_basePos(basePos) {}
53
55 PERM* at(unsigned long val) const {
56 for (unsigned int i=0; i<m_basePos; ++i) {
57 if ((symmetricGroup->B)[i] == val)
58 return 0;
59 }
60
61 PERM* p = new PERM(symmetricGroup->B.size());
62 p->setTransposition((symmetricGroup->B)[m_basePos],val);
63 return p;
64 }
65
67 unsigned int size() const { return symmetricGroup->n - m_basePos; }
68
69 boost::counting_iterator<unsigned int> begin() const { return boost::counting_iterator<unsigned int>(0); };
70 boost::counting_iterator<unsigned int> end() const { return boost::counting_iterator<unsigned int>(symmetricGroup->n-m_basePos ); };
71 private:
72 const SymmetricGroup<PERM>* symmetricGroup;
73 unsigned int m_basePos;
74};
75
76}
77
78#endif // SYMMETRIC_GROUP_TRANSVERSAL_H_
79
transversal of a symmetric group
Definition symmetric_group_transversal.h:45
unsigned int size() const
size of basic orbit / transversal
Definition symmetric_group_transversal.h:67
PERM * at(unsigned long val) const
computes a transversal element on demand if one exists
Definition symmetric_group_transversal.h:55
SymmetricGroupTransversal(const SymmetricGroup< PERM > *sg, unsigned int basePos)
constructs a transversal of a symmetric group
Definition symmetric_group_transversal.h:52
representation of a symmetric group
Definition symmetric_group.h:52