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// Copyright (C) 1995 The New York Group Theory Cooperative
// See magnus/doc/COPYRIGHT for the full notice.
// Contents: Definition of MSCGConjugacyProblem class.
// This is a solving of conjugacy problem for metric
// small cancellation groups with C'(1/6) condition.
//
// Principal Authors: Dmitry Bormotov
//
// Status: in progress
//
// Revision History:
//
// Special Remarks:
//
//
#ifndef _MSCG_CONJUGACY_PROBLEM_H_
#define _MSCG_CONJUGACY_PROBLEM_H_
#include "MSCGroup.h"
// ------------------------ MSCGConjugacyProblem ---------------------------//
class MSCGConjugacyProblem {
public:
/////////////////////////////////////////////////////////////////////////
// //
// Constructors: //
// //
/////////////////////////////////////////////////////////////////////////
// No default constructor
// Copy constructor provided by compiler (does logical deep copy).
MSCGConjugacyProblem ( const MSCGroup& G, const Word& u, const Word& v ) :
MSCG ( G ), U( u.freelyReduce() ), V( v.freelyReduce() ),
areConjugate ( DONTKNOW ), theConjugator ( ), doneStatus ( false ),
startStatus ( false ), UConjugator( ), VConjugator( ) { };
// To construct a conjugacy problem class with given MSCGroup.
/////////////////////////////////////////////////////////////////////////
// //
// Activation members: //
// //
/////////////////////////////////////////////////////////////////////////
void startComputation( );
// Start the computation.
// You shouldn't call this more than one time.
bool continueComputation( );
// Advance the computation of conjugacy problem.
// You have to call startComputation() before.
// This function returns true if the computation is done.
/////////////////////////////////////////////////////////////////////////
// //
// Status Queries: //
// //
/////////////////////////////////////////////////////////////////////////
bool done( ) const {
return doneStatus;
}
// Is the conjugacy problem done ?
/////////////////////////////////////////////////////////////////////////
// //
// Accessors: //
// //
/////////////////////////////////////////////////////////////////////////
// You can call all these functions iff the computation is finished
// ( when the done() functions returns true ).
Trichotomy answer( ) const {
#if SAFETY > 0
if ( !doneStatus )
error("tried to get answer of conjugate problem before solve it");
#endif
return areConjugate;
}
// Are the words conjugate ?
Word conjugator( ) const {
#if SAFETY > 0
if ( answer() != YES )
if ( answer() == NO )
error("tried to get conjugator when the words aren't conjugate");
else
error("tried to get conjugator when result the conjugacy"
" problem is unknown");
#endif
return theConjugator;
}
private:
/////////////////////////////////////////////////////////////////////////
// //
// Private Functions: //
// //
/////////////////////////////////////////////////////////////////////////
MSCGConjugacyProblem( const MSCGConjugacyProblem& );
// It is hidden, not implemented.
MSCGConjugacyProblem& operator = ( const MSCGConjugacyProblem& );
// It is hidden, not implemented.
void setCPResult( Trichotomy result );
// Set result of conjugacy problem and reset status variables.
void finishCP( Trichotomy result );
// Finish conjugacy problem ( delete all objects and set result).
/////////////////////////////////////////////////////////////////////////
// //
// Data Members: //
// //
/////////////////////////////////////////////////////////////////////////
const MSCGroup& MSCG; // The MSC group in which we solve a
// conjugacy problem
bool doneStatus; // TRUE if the computation is finished
bool startStatus; // TRUE if the computation is started
Trichotomy areConjugate; // the result of conjugacy problem
Word theConjugator; // the conjugator if the words are conjugate
int maxLen; // maximal length of relators which we
// need use for generating pieces
Word UConjugator;
Word VConjugator;
// This variables contain information for iterations of conjugacy problem
enum stateType{CYCLE_BY_RELATORS, CYCLE_BY_PIECES, CYCLE_BY_RELATORS2};
stateType state; // In what kind of cycle we are now ?
bool firstPart; // TRUE if we are in first part of algorithm:
// for C'(1/8) condition
Word U; // fisrt argument for conjugacy problem
Word V; // second argument for conjugacy problem
int ULen; // length of U
int VLen; // length of V
SetOf<Word> cycV; // the set of cyclic permutations of V
SymmetricRelators *shortRelators;
// The set of short relators.
// Only this relators would be able to shorten given word
SymmetricRelatorsIterator *shortIter; // symmetric iterators over the
SymmetricRelatorsIterator *shortIter2; // set of relators
Word relator; // current relator
int relatorLen; // its length
int pieceLen; // tne length of current piece of current relator
Word relatorOne; // the first current relator
int relatorOneLen; // its length
int pieceOneLen; // the length of fisrt piece of relatorOne
Word pieceOne; // the fisrt piece of relatorOne
Word relatorTwo; // the second current relator
int relatorTwoLen; // its length
/////////////////////////////////////////////////////////////////////////
// //
// Debugging stuff: //
// //
/////////////////////////////////////////////////////////////////////////
#ifdef DEBUG
friend int main(int, char**);
#endif
};
#endif
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