permlib
0.2.6
Library for permutation computations
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00001 // --------------------------------------------------------------------------- 00002 // 00003 // This file is part of PermLib. 00004 // 00005 // Copyright (c) 2009-2011 Thomas Rehn <thomas@carmen76.de> 00006 // All rights reserved. 00007 // 00008 // Redistribution and use in source and binary forms, with or without 00009 // modification, are permitted provided that the following conditions 00010 // are met: 00011 // 1. Redistributions of source code must retain the above copyright 00012 // notice, this list of conditions and the following disclaimer. 00013 // 2. Redistributions in binary form must reproduce the above copyright 00014 // notice, this list of conditions and the following disclaimer in the 00015 // documentation and/or other materials provided with the distribution. 00016 // 3. The name of the author may not be used to endorse or promote products 00017 // derived from this software without specific prior written permission. 00018 // 00019 // THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 00020 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 00021 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 00022 // IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 00023 // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 00024 // NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 00025 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 00026 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 00027 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 00028 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 00029 // 00030 // --------------------------------------------------------------------------- 00031 00032 00033 #ifndef GROUPINTERSECTIONPREDICATE_H_ 00034 #define GROUPINTERSECTIONPREDICATE_H_ 00035 00036 #include <permlib/bsgs.h> 00037 #include <permlib/predicate/subgroup_predicate.h> 00038 00039 #include <boost/foreach.hpp> 00040 00041 namespace permlib { 00042 00044 template <class PERM, class TRANS> 00045 class GroupIntersectionPredicate : public SubgroupPredicate<PERM> { 00046 public: 00048 00052 GroupIntersectionPredicate(const BSGS<PERM, TRANS> &g, const BSGS<PERM, TRANS> &h); 00053 00054 virtual bool operator()(const PERM &p) const; 00055 virtual bool childRestriction(const PERM &h, unsigned int i, unsigned long beta_i) const; 00056 virtual unsigned int limit() const; 00057 private: 00058 const BSGS<PERM, TRANS> &m_G; 00059 const BSGS<PERM, TRANS> &m_H; 00060 }; 00061 00062 // 00063 // ---- IMPLEMENTATION 00064 // 00065 00066 template <class PERM, class TRANS> 00067 GroupIntersectionPredicate<PERM,TRANS>::GroupIntersectionPredicate(const BSGS<PERM, TRANS> &g, const BSGS<PERM, TRANS> &h) 00068 : m_G(g), m_H(h) 00069 { 00070 BOOST_ASSERT(m_G.n == m_H.n); 00071 BOOST_ASSERT(m_G.order() <= m_H.order()); 00072 } 00073 00074 template <class PERM, class TRANS> 00075 bool GroupIntersectionPredicate<PERM,TRANS>::operator()(const PERM &p) const { 00076 return m_G.sifts(p) && m_H.sifts(p); 00077 } 00078 00079 template <class PERM, class TRANS> 00080 bool GroupIntersectionPredicate<PERM,TRANS>::childRestriction(const PERM &h, unsigned int i, unsigned long beta_i) const { 00081 //TODO: check \beta_l^{g h^{-1}} \in \beta_l^{H_{(beta_1 ... beta_{l-1})}} instead 00082 // cf. Handbook of Computational Group Theory, sec 4.6.6 00083 PERM siftee(m_H.n); 00084 const unsigned int m = m_H.sift(h, siftee, 0, i+1); 00085 return i+1 == m; 00086 } 00087 00088 template <class PERM, class TRANS> 00089 unsigned int GroupIntersectionPredicate<PERM,TRANS>::limit() const { 00090 return m_G.B.size(); 00091 } 00092 00093 } 00094 00095 #endif // -- GROUPINTERSECTIONPREDICATE_H_