Since it is hard to establish relations between entities E, which are domain dependent, we try to approximate these relations by using logical flow of Q and A, expressible in domain-independent terms, such as rhetorical relation.
hence we require a certain correspondence between DT-Q and DT-A, considering additional labels for DT nodes by entities (we denote such DT as EDT): (2) a common case is that some entities E are not explicitly mentioned in Q but instead are assumed.