symmetric_group.h

// ---------------------------------------------------------------------------
//
//  This file is part of PermLib.
//
// Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de>
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
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// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
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//    derived from this software without specific prior written permission.
// 
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// ---------------------------------------------------------------------------
 
 
#ifndef SYMMETRICGROUP_H_
#define SYMMETRICGROUP_H_
 
#include <permlib/bsgs_core.h>
#include <permlib/transversal/symmetric_group_transversal.h>
 
#include <boost/shared_ptr.hpp>
 
namespace permlib {


template<class PERM>
struct SymmetricGroup : public BSGSCore<PERM, SymmetricGroupTransversal<PERM> > {
        explicit SymmetricGroup(unsigned int n);
        SymmetricGroup(const SymmetricGroup<PERM>& symGroup);
        SymmetricGroup& operator=(const SymmetricGroup<PERM>& symGroup);
        
        typedef SymmetricGroupTransversal<PERM> TRANS;
        
        virtual bool isSymmetricGroup() const { return true; }
private:
        void copy(const SymmetricGroup<PERM>& symGroup);
};
 
template<class PERM>
inline SymmetricGroup<PERM>::SymmetricGroup(unsigned int n_)
        : BSGSCore<PERM,TRANS>(-n_, n_, n_)
{
        BOOST_ASSERT(this->n > 0);
        BSGSCore<PERM,TRANS>::U.reserve(this->n);
        for (unsigned int i = 0; i < this->n; ++i) {
                BSGSCore<PERM,TRANS>::B[i] = this->n-1-i;
                BSGSCore<PERM,TRANS>::U.push_back(SymmetricGroupTransversal<PERM>(this, i));
                if (i < static_cast<unsigned int>(this->n-1)) {
                        boost::shared_ptr<PERM> gen(new PERM(this->n));
                        gen->setTransposition(i, i+1);
                        BSGSCore<PERM,TRANS>::S.push_back(gen);
                }
        }
}
 
template<class PERM>
inline void SymmetricGroup<PERM>::copy(const SymmetricGroup<PERM>& symGroup) 
{
        const unsigned long& n2 = symGroup.n;
        BSGSCore<PERM,TRANS>::U.reserve(n2);
        for (unsigned int i = 0; i < n2; ++i) {
                BSGSCore<PERM,TRANS>::B[i] = symGroup.B[i];
                BSGSCore<PERM,TRANS>::U.push_back(SymmetricGroupTransversal<PERM>(this, i));
                if (i < n2-1) {
                        boost::shared_ptr<PERM> gen(new PERM(n2));
                        gen->setTransposition(i, i+1);
                        BSGSCore<PERM,TRANS>::S.push_back(gen);
                }
        }
}
 
template<class PERM>
inline SymmetricGroup<PERM>::SymmetricGroup(const SymmetricGroup<PERM>& symGroup) 
        : BSGSCore<PERM,TRANS>(-symGroup.n, symGroup.n, symGroup.n)
{
        copy(symGroup);
}
 
template<class PERM>
inline SymmetricGroup<PERM>& SymmetricGroup<PERM>::operator=(const SymmetricGroup<PERM>& symGroup) 
{
        BOOST_ASSERT(symGroup.n == this->n);
        
        BSGSCore<PERM,TRANS>::n = symGroup.n;
        BSGSCore<PERM,TRANS>::m_id = symGroup.m_id;
        copy(symGroup);
        return *this;
}
 
}
 
 
#endif // SYMMETRICGROUP_H_