src/theory/arith/tableau.cpp

   1 /*********************                                                        */
   2 /*! \file tableau.cpp
   3  ** \verbatim
   4  ** Original author: taking
   5  ** Major contributors: none
   6  ** Minor contributors (to current version): none
   7  ** This file is part of the CVC4 prototype.
   8  ** Copyright (c) 2009, 2010  The Analysis of Computer Systems Group (ACSys)
   9  ** Courant Institute of Mathematical Sciences
  10  ** New York University
  11  ** See the file COPYING in the top-level source directory for licensing
  12  ** information.\endverbatim
  13  **
  14  ** \brief [[ Add one-line brief description here ]]
  15  **
  16  ** [[ Add lengthier description here ]]
  17  ** \todo document this file
  18  **/
  19
  20
  21 #include "theory/arith/tableau.h"
  22
  23 using namespace CVC4;
  24 using namespace CVC4::theory;
  25 using namespace CVC4::theory::arith;
  26
  27 void Tableau::addRow(ArithVar basicVar,
  28                      const std::vector<Rational>& coeffs,
  29                      const std::vector<ArithVar>& variables){
  30
  31   Assert(coeffs.size() == variables.size());
  32   Assert(d_basicManager.isMember(basicVar));
  33
  34   //The new basic variable cannot already be a basic variable
  35   Assert(!d_activeBasicVars.isMember(basicVar));
  36   d_activeBasicVars.add(basicVar);
  37   ReducedRowVector* row_current = new ReducedRowVector(basicVar,variables, coeffs,d_rowCount);
  38   d_rowsTable[basicVar] = row_current;
  39
  40   //A variable in the row may have been made non-basic already.
  41   //If this is the case we fake pivoting this variable
  42   vector<ArithVar>::const_iterator varsIter = variables.begin();
  43   vector<ArithVar>::const_iterator varsEnd = variables.end();
  44
  45   for( ; varsIter != varsEnd; ++varsIter){
  46     ArithVar var = *varsIter;
  47
  48     if(d_basicManager.isMember(var)){
  49       Assert(d_activeBasicVars.isMember(var));
  50
  51       ReducedRowVector& row_var = lookup(var);
  52       row_current->substitute(row_var);
  53     }
  54   }
  55 }
  56
  57 ReducedRowVector* Tableau::removeRow(ArithVar basic){
  58   Assert(d_basicManager.isMember(basic));
  59   Assert(d_activeBasicVars.isMember(basic));
  60
  61   ReducedRowVector* row = d_rowsTable[basic];
  62
  63   d_activeBasicVars.remove(basic);
  64   d_rowsTable[basic] = NULL;
  65
  66   return row;
  67 }
  68
  69 void Tableau::pivot(ArithVar x_r, ArithVar x_s){
  70   Assert(d_basicManager.isMember(x_r));
  71   Assert(!d_basicManager.isMember(x_s));
  72
  73   Debug("tableau") << "Tableau::pivot(" <<  x_r <<", " <<x_s <<")"  << endl;
  74
  75   ReducedRowVector* row_s = d_rowsTable[x_r];
  76   Assert(row_s != NULL);
  77   Assert(row_s->has(x_s));
  78
  79   //Swap x_r and x_s in d_activeRows
  80   d_rowsTable[x_s] = row_s;
  81   d_rowsTable[x_r] = NULL;
  82
  83   d_activeBasicVars.remove(x_r);
  84   d_basicManager.remove(x_r);
  85
  86   d_activeBasicVars.add(x_s);
  87   d_basicManager.add(x_s);
  88
  89   row_s->pivot(x_s);
  90
  91   for(ArithVarSet::iterator basicIter = begin(), endIter = end();
  92       basicIter != endIter; ++basicIter){
  93     ArithVar basic = *basicIter;
  94     if(basic == x_s) continue;
  95
  96     ReducedRowVector& row_k = lookup(basic);
  97     if(row_k.has(x_s)){
  98       row_k.substitute(*row_s);
  99     }
 100   }
 101 }
 102 void Tableau::printTableau(){
 103   Debug("tableau") << "Tableau::d_activeRows"  << endl;
 104
 105   typedef RowsTable::iterator table_iter;
 106   for(table_iter rowIter = d_rowsTable.begin(), end = d_rowsTable.end();
 107       rowIter != end; ++rowIter){
 108     ReducedRowVector* row_k = *rowIter;
 109     if(row_k != NULL){
 110       row_k->printRow();
 111     }
 112   }
 113 }