@Override
public void explain(Deduction d, Explanation e) {
e.add(solver.getExplainer().getPropagatorActivation(this));
e.add(aCause);
Variable reason = (d.getVar() == vars[0]) ? vars[1] : vars[0];
reason.explain(VariableState.DOM, e);
}
@Override
public void duplicate(Solver solver, THashMap<Object, Object> identitymap) {
if (!identitymap.containsKey(this)) {