33 #ifndef SCHREIERSIMSCONSTRUCTION_H_ 34 #define SCHREIERSIMSCONSTRUCTION_H_ 36 #include <permlib/construct/base_construction.h> 37 #include <permlib/bsgs.h> 38 #include <permlib/generator/schreier_generator.h> 40 #include <boost/foreach.hpp> 45 template <
class PERM,
class TRANS>
57 template <
class ForwardIterator>
67 template <
class ForwardIterator,
class InputIterator>
68 BSGS<PERM, TRANS> construct(ForwardIterator generatorsBegin, ForwardIterator generatorsEnd, InputIterator prescribedBaseBegin, InputIterator prescribedBaseEnd)
const;
78 template <
class PERM,
class TRANS>
83 template <
class PERM,
class TRANS>
84 template <
class ForwardIterator>
89 template <
class PERM,
class TRANS>
90 template <
class ForwardIterator,
class InputIterator>
92 ::construct(ForwardIterator generatorsBegin, ForwardIterator generatorsEnd, InputIterator prescribedBaseBegin, InputIterator prescribedBaseEnd)
const 94 const dom_int &n = this->m_n;
96 std::vector<dom_int> &B = ret.
B;
97 std::vector<TRANS> &U = ret.
U;
98 std::vector<std::list<typename PERM::ptr> > S;
99 this->setup(generatorsBegin, generatorsEnd, prescribedBaseBegin, prescribedBaseEnd, ret, S);
101 std::vector<boost::shared_ptr<SchreierGenerator<PERM, TRANS> > > SchreierGens;
102 for (
unsigned int i = 0; i < B.size(); ++i) {
103 BOOST_ASSERT( i < U.size() );
104 BOOST_ASSERT( i < S.size() );
108 unsigned int j = B.size();
109 bool breakUp =
false;
113 sg.
update(&U[j-1], S[j-1].begin(), S[j-1].end());
116 ++m_statScheierGeneratorsConsidered;
117 PERMLIB_DEBUG(
for(
unsigned int jjj=0; jjj<j; ++jjj) std::cout <<
" ";)
118 PERMLIB_DEBUG(std::cout <<
"schreier j = " << (j-1) <<
" [" << S[j-1].size() <<
"," << U[j-1].size() <<
"]: ";)
122 unsigned int k = ret.
sift(g, h, j);
123 if (k < B.size() - j || !h.isIdentity()) {
132 BOOST_ASSERT(j < B.size());
133 S.push_back(std::list<typename PERM::ptr>());
134 U.push_back(TRANS(n));
136 boost::shared_ptr<PERM> hPtr(
new PERM(h));
137 S[j].insert(S[j].end(), hPtr);
140 if (j >= SchreierGens.size()) {
142 SchreierGens.push_back(localVar);
144 SchreierGens[j]->update(S[j].size() - 1);
156 this->mergeGenerators(S, ret);
163 #endif // -- SCHREIERSIMSCONSTRUCTION_H_ void orbitUpdate(unsigned int j, const PERMlist &generators, const typename PERM::ptr &g)
updates the j-th fundamental orbit with the given orbit generators and a new generator g ...
Definition: bsgs.h:305
bool chooseBaseElement(const PERM &h, dom_int &beta) const
tries to find a new base element
Definition: bsgs.h:289
stateful generator of Schreier generators
Definition: schreier_generator.h:54
BSGS< PERM, TRANS > construct(ForwardIterator generatorsBegin, ForwardIterator generatorsEnd) const
constructs a BSGS for group given by generators with no base prescribed
Definition: schreier_sims_construction.h:85
SchreierSimsConstruction(unsigned int n)
constructor
Definition: schreier_sims_construction.h:79
void update(TRANS *U, PERMlistIt S_begin, PERMlistIt S_end)
updates transversal and group generators that the Schreier generators are constructed from ...
Definition: schreier_generator.h:215
unsigned int sift(const PERM &g, PERM &siftee, unsigned int j=0) const
sifts an element through the specified transversal range
Definition: bsgs.h:272
std::vector< dom_int > B
base
Definition: bsgs_core.h:55
base class for BSGS construction algorithms
Definition: base_construction.h:46
unsigned int m_statScheierGeneratorsConsidered
number of Schreier generators examined during the last construct call
Definition: schreier_sims_construction.h:71
Represents a base and strong generating set (BSGS)
Definition: bsgs.h:58
std::vector< TRANS > U
transversals along the stabilizer chain
Definition: bsgs_core.h:59
PERM next()
generates an element
Definition: schreier_generator.h:184
BSGS construction with classic Schreier-Sims algorithm.
Definition: schreier_sims_construction.h:46
Definition: abstract_bsgs.h:49
bool hasNext()
true, iff more elements can be generated
Definition: schreier_generator.h:141