permlib  0.2.9
Library for permutation computations
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
20 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 // IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 // NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 //
30 // ---------------------------------------------------------------------------
31 
32 
33 #ifndef BASECHANGE_H_
34 #define BASECHANGE_H_
35 
36 #include <permlib/predicate/pointwise_stabilizer_predicate.h>
37 
38 namespace permlib {
39 
41 
45 template<class PERM,class TRANS>
46 class BaseChange {
47 public:
50 
52  mutable unsigned int m_statTranspositions;
53 
55  mutable unsigned int m_statScheierGeneratorsConsidered;
56 protected:
58 
63  bool isRedundant(const BSGSCore<PERM,TRANS>& bsgs, unsigned int baseTargetPos, unsigned long alpha) const;
64 };
65 
66 template<class PERM,class TRANS>
67 bool 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_
abstract base class for base change algorithms
Definition: base_change.h:46
BaseChange()
constructor
Definition: base_change.h:49
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
core data of a base and strong generating set (BSGS)
Definition: bsgs_core.h:42
predicate matching a permutation if it stabilizes a given list of points pointwise ...
Definition: pointwise_stabilizer_predicate.h:42
std::vector< dom_int > B
base
Definition: bsgs_core.h:55
unsigned int m_statScheierGeneratorsConsidered
nuber of Schreier generators considered in transposition since construction
Definition: base_change.h:55
PERMlist S
strong generating set
Definition: bsgs_core.h:57
Definition: abstract_bsgs.h:49
unsigned int m_statTranspositions
nuber of base transpositions needed since construction
Definition: base_change.h:52