WitnessImprovement FCSimplexDecisionProcedure::focusUsingSignDisagreements(ArithVar basic){
Assert(!d_sgnDisagreements.empty());
Assert(d_errorSet.focusSize() >= 2);
if(Debug.isOn("arith::focus")){
d_errorSet.debugPrint(Debug("arith::focus"));
}
ArithVar nb = d_linEq.minBy(d_sgnDisagreements, &LinearEqualityModule::minColLength);
const Tableau::Entry& e_evar_nb = d_tableau.basicFindEntry(basic, nb);
int oppositeSgn = - (e_evar_nb.getCoefficient().sgn());
Debug("arith::focus") << "focusUsingSignDisagreements " << basic << " " << oppositeSgn << endl;
ArithVarVec dropped;
Tableau::ColIterator colIter = d_tableau.colIterator(nb);
for(; !colIter.atEnd(); ++colIter){
const Tableau::Entry& entry = *colIter;
Assert(entry.getColVar() == nb);
int sgn = entry.getCoefficient().sgn();
Debug("arith::focus")
<< "on row "
<< d_tableau.rowIndexToBasic(entry.getRowIndex())
<< " "
<< entry.getCoefficient() << endl;
ArithVar currRow = d_tableau.rowIndexToBasic(entry.getRowIndex());
if(d_errorSet.inError(currRow) && d_errorSet.inFocus(currRow)){
int errSgn = d_errorSet.getSgn(currRow);
if(errSgn * sgn == oppositeSgn){
dropped.push_back(currRow);
Debug("arith::focus") << "dropping from focus " << currRow << endl;
}
}
}
d_sgnDisagreements.clear();
return adjustFocusShrank(dropped);
}
Result::Sat AttemptSolutionSDP::attempt(const ApproximateSimplex::Solution& sol){
const DenseSet& newBasis = sol.newBasis;
const DenseMap<DeltaRational>& newValues = sol.newValues;
DenseSet needsToBeAdded;
for(DenseSet::const_iterator i = newBasis.begin(), i_end = newBasis.end(); i != i_end; ++i){
ArithVar b = *i;
if(!d_tableau.isBasic(b)){
needsToBeAdded.add(b);
}
}
DenseMap<DeltaRational>::const_iterator nvi = newValues.begin(), nvi_end = newValues.end();
for(; nvi != nvi_end; ++nvi){
ArithVar currentlyNb = *nvi;
if(!d_tableau.isBasic(currentlyNb)){
if(!matchesNewValue(newValues, currentlyNb)){
const DeltaRational& newValue = newValues[currentlyNb];
Trace("arith::updateMany")
<< "updateMany:" << currentlyNb << " "
<< d_variables.getAssignment(currentlyNb) << " to "<< newValue << endl;
d_linEq.update(currentlyNb, newValue);
Assert(d_variables.assignmentIsConsistent(currentlyNb));
}
}
}
d_errorSet.reduceToSignals();
d_errorSet.setSelectionRule(VAR_ORDER);
static int instance = 0;
++instance;
if(processSignals()){
Debug("arith::findModel") << "attemptSolution("<< instance <<") early conflict" << endl;
d_conflictVariables.purge();
return Result::UNSAT;
}else if(d_errorSet.errorEmpty()){
Debug("arith::findModel") << "attemptSolution("<< instance <<") fixed itself" << endl;
return Result::SAT;
}
while(!needsToBeAdded.empty() && !d_errorSet.errorEmpty()){
ArithVar toRemove = ARITHVAR_SENTINEL;
ArithVar toAdd = ARITHVAR_SENTINEL;
DenseSet::const_iterator i = needsToBeAdded.begin(), i_end = needsToBeAdded.end();
for(; toAdd == ARITHVAR_SENTINEL && i != i_end; ++i){
ArithVar v = *i;
Tableau::ColIterator colIter = d_tableau.colIterator(v);
for(; !colIter.atEnd(); ++colIter){
const Tableau::Entry& entry = *colIter;
Assert(entry.getColVar() == v);
ArithVar b = d_tableau.rowIndexToBasic(entry.getRowIndex());
if(!newBasis.isMember(b)){
toAdd = v;
bool favorBOverToRemove =
(toRemove == ARITHVAR_SENTINEL) ||
(matchesNewValue(newValues, toRemove) && !matchesNewValue(newValues, b)) ||
(d_tableau.basicRowLength(toRemove) > d_tableau.basicRowLength(b));
if(favorBOverToRemove){
toRemove = b;
}
}
}
}
Assert(toRemove != ARITHVAR_SENTINEL);
Assert(toAdd != ARITHVAR_SENTINEL);
Trace("arith::forceNewBasis") << toRemove << " " << toAdd << endl;
//Message() << toRemove << " " << toAdd << endl;
d_linEq.pivotAndUpdate(toRemove, toAdd, newValues[toRemove]);
Trace("arith::forceNewBasis") << needsToBeAdded.size() << "to go" << endl;
//Message() << needsToBeAdded.size() << "to go" << endl;
needsToBeAdded.remove(toAdd);
bool conflict = processSignals();
if(conflict){
d_errorSet.reduceToSignals();
d_conflictVariables.purge();
return Result::UNSAT;
}
}
Assert( d_conflictVariables.empty() );
if(d_errorSet.errorEmpty()){
return Result::SAT;
}else{
d_errorSet.reduceToSignals();
return Result::SAT_UNKNOWN;
}
}