known_bsgs_construction.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
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// ---------------------------------------------------------------------------
 
 
#ifndef KNOWNBSGSCONSTRUCTION_H_
#define KNOWNBSGSCONSTRUCTION_H_
 
#include <permlib/construct/base_construction.h>
#include <permlib/bsgs.h>
 
namespace permlib {

template <class PERM, class TRANS>
class KnownBSGSConstruction : public BaseConstruction<PERM, TRANS> {
public:

        KnownBSGSConstruction(unsigned int n);


        template <class ForwardIterator, class InputIterator>
        BSGS<PERM, TRANS> construct(ForwardIterator generatorsBegin, ForwardIterator generatorsEnd, InputIterator knownBaseBegin, InputIterator knownBaseEnd) const;
};
 
//
//     ----       IMPLEMENTATION
//
 
template <class PERM, class TRANS>
KnownBSGSConstruction<PERM,TRANS>::KnownBSGSConstruction(unsigned int n) 
        : BaseConstruction<PERM, TRANS>(n)
{ }
 
 
template <class PERM, class TRANS>
template <class ForwardIterator, class InputIterator>
BSGS<PERM, TRANS> KnownBSGSConstruction<PERM, TRANS>
        ::construct(ForwardIterator generatorsBegin, ForwardIterator generatorsEnd, InputIterator knownBaseBegin, InputIterator knownBaseEnd) const
{
        const unsigned int &n = this->m_n;
        BSGS<PERM, TRANS> ret(n);
        std::vector<std::list<typename PERM::ptr> > S;
        this->setup(generatorsBegin, generatorsEnd, knownBaseBegin, knownBaseEnd, ret, S);
        BOOST_ASSERT( S.size() > 0 );
        // the strong generating set of the group is the
        // stabilizer of the empty set of the given generators
        ret.S.insert(ret.S.end(), S[0].begin(), S[0].end());
        return ret;
}
 
}
 
#endif // -- KNOWNBSGSCONSTRUCTION_H_