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);
}