}
}
else if (successor.getClass() == CoGroupNode.class) {
CoGroupNode cg = (CoGroupNode) successor;
if (cg.getFirstPredecessorNode() == solutionSetNode) {
cg.makeCoGroupWithSolutionSet(0);
} else if (cg.getSecondPredecessorNode() == solutionSetNode) {
cg.makeCoGroupWithSolutionSet(1);
} else {
throw new CompilerException();
}