Referential actions are specialized triggers for automatically maintaining referential integrity in databases. While the  local effects  of referential actions can be grasped easily, it is far from obvious what the  global semantics  of a set of interacting referential actions should be. In particular, when using procedural execution models, ambiguities due to the execution ordering can occur. No  global, declarative  semantics of referential actions has yet been defined.We show that the well-known logic programming semantics provide a natural  global  semantics of referential actions that is based on their  local  characterization: To capture the global meaning of a set  RA  of referential actions, we first define their abstract (but non-constructive)  intended semantics . Next, we  formalize RA  as a  logic program   P RA  . The declarative, logic programming semantics of  P RA   then provide the constructive,  global  semantics of the referential actions. So, we do not  define  a semantics for referential actions, but we show that there  exists  a unique  natural  semantics if one is ready to accept (i) the intuitive local semantics of local referential actions, (ii) the formalization of those and of the local "effect-propagating" rules, and (iii) the well-founded or stable model semantics from logic programming as "reasonable" global semantics for local rules.We first focus on the subset of referential actions for deletions only. We prove the equivalence of the logic programming semantics and the abstract semantics via a game-theoretic characterization, which provides additional insight into the meaning of interacting referential actions. In this case a  unique maximal admissible solution exists , computable by a ptime algorithm.Second, we investigate the general case---including modifications. We show that in this case there can be  multiple maximal admissible subsets  and that all maximal admissible subsets can be characterized as  3-valued stable models  of  P RA  . We show that for a given set of user requests, in the presence of referential actions of the form ON UPDATE CASCADE, the admissibility check and the computation of the subsequent database state, and (for non-admissible updates) the derivation of debugging hints all are in ptime. Thus, full referential actions can be implemented efficiently.
['Wolfgang May', 'Bertram Ludäscher']
Understanding the global semantics of referential actions using logic rules