Abstract not found

this paper, we extend XML DTDs with several classes of integrity constraints and investigate the complexity of reasoning about these constraints. The constraints range over keys, foreign keys, inverse constraints as well as ID constraints for capturing the semantics of object identities. They improve semantic specifications and provide a better reference mechanism for native XML applications. They are also useful in information exchange and data integration for preserving the semantics of data originating in relational and object-oriented databases. We establish complexity and axiomatization results for the (finite) implication problems associated with these constraints. In addition, we study implication of more general constraints, such as functional, inclusion and inverse constraints defined in terms of navigation paths

We investigate finite implication problems associated with key and foreign key constraints for XML data. We demonstrate that there is interaction between DTDs and these constraints, and the interaction complicates the analysis of finite implication. In particular, we establish complexity results for reasoning about two classes of constraints for XML. One class, L u , defines unary keys and foreign keys, and the other, L, consists of multi-attribute keys and foreign keys. We show that the finite implication problem for L u constraints is coNP-complete, and the finite implication problem for L constraints is undecidable. We also identify several PTIME decidable cases of the finite implication problems. In addition, we improve the results established in [16] by showing that the finite satisfiability problem for unary keys, unary inclusion constraints and their negations is NP-complete.