/** Return the derivation of at triple. The derivation is a List of DerivationRecords */
@Override
public Iterator<Derivation> getDerivation(Triple t) {
if (derivations == null) {
return new NullIterator<Derivation>();
} else {
return derivations.getAll(t);
}
}
/** Log a dervivation record against the given triple. */
@Override
public void logDerivation(Triple t, Derivation derivation) {
derivations.put(t, derivation);
}