@Override
public Result execute() {
Result inResult1 = getInputTerm1().execute();
Result inResult2 = getInputTerm2().execute();
DifferenceSetOperator oper = new DifferenceSetOperator(Utils.getCaf(), inResult1.getResultRelation(), inResult2.getResultRelation());
inResult1.extend(inResult2);
inResult1.extend(oper);
storeResult(inResult1);
return inResult1;
}