Multivalued Dependencies for XML Documents with DTDs

Besides functional dependencies, multivalued dependencies are also important integrity constrains in XML documents. So far, the definitions for multivalued dependencies are oriented to XML documents, rather than schemata. At present, DTD is accepted to be a major schema for a XML document, and most of XML documents are designed to have DTDs. So, it is necessary to propose a definition about multivalued dependencies in XML documents with DTDs. We define the multivalued dependency on the DTD and give its semantics via a relational representation of XML. Then, we investigate the issues related to logical implication of multivalued dependencies, give the definitions of closure, path dependency basis and the closure of paths of multivalued dependencies for XML, propose a set of inference rules which are sound and complete. Finally, we propose an algorithm to compute the path dependency basis and an algorithm to decide the membership between a given multivalued dependency and a set of multivalued dependencies.