permlib 0.2.9
Library for permutation computations
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base_change.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.
7//
8// Redistribution and use in source and binary forms, with or without
9// modification, are permitted provided that the following conditions
10// are met:
11// 1. Redistributions of source code must retain the above copyright
12// notice, this list of conditions and the following disclaimer.
13// 2. Redistributions in binary form must reproduce the above copyright
14// notice, this list of conditions and the following disclaimer in the
15// documentation and/or other materials provided with the distribution.
16// 3. The name of the author may not be used to endorse or promote products
17// derived from this software without specific prior written permission.
18//
19// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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21// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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29//
30// ---------------------------------------------------------------------------
31
32
33#ifndef BASECHANGE_H_
34#define BASECHANGE_H_
35
36#include <permlib/predicate/pointwise_stabilizer_predicate.h>
37
38namespace permlib {
39
41
45template<class PERM,class TRANS>
47public:
50
52 mutable unsigned int m_statTranspositions;
53
56protected:
58
63 bool isRedundant(const BSGSCore<PERM,TRANS>& bsgs, unsigned int baseTargetPos, unsigned long alpha) const;
64};
65
66template<class PERM,class TRANS>
67bool BaseChange<PERM,TRANS>::isRedundant(const BSGSCore<PERM,TRANS>& bsgs, unsigned int baseTargetPos, unsigned long alpha) const {
68 bool redundant = true;
69 const PointwiseStabilizerPredicate<PERM> stab_i(bsgs.B.begin(), bsgs.B.begin() + baseTargetPos);
70 BOOST_FOREACH(const typename PERM::ptr& g, bsgs.S) {
71 if (!stab_i(g))
72 continue;
73 if (*g / alpha != alpha) {
74 redundant = false;
75 break;
76 }
77 }
78
79#ifdef PERMLIB_DEBUG_OUTPUT
80 if (redundant) {
81 std::cout << "skip redundant " << (alpha+1) << std::endl;
82 print_iterable(bsgs.B.begin(), bsgs.B.begin() + baseTargetPos, 1, " redundant for");
83 } else {
84 std::cout << "look for " << (alpha+1) << " at position " << baseTargetPos << std::endl;
85 }
86#endif
87
88 return redundant;
89}
90
91}
92
93#endif // -- BASECHANGE_H_
unsigned int m_statScheierGeneratorsConsidered
nuber of Schreier generators considered in transposition since construction
Definition base_change.h:55
bool isRedundant(const BSGSCore< PERM, TRANS > &bsgs, unsigned int baseTargetPos, unsigned long alpha) const
checks if insertion of a base point at given position is redundant
Definition base_change.h:67
unsigned int m_statTranspositions
nuber of base transpositions needed since construction
Definition base_change.h:52
BaseChange()
constructor
Definition base_change.h:49
predicate matching a permutation if it stabilizes a given list of points pointwise
Definition pointwise_stabilizer_predicate.h:42
core data of a base and strong generating set (BSGS)
Definition bsgs_core.h:42
std::vector< dom_int > B
base
Definition bsgs_core.h:55
PERMlist S
strong generating set
Definition bsgs_core.h:57