Characterization of the interaction of XML functional dependencies with DTDs

Abstract

With the rise of XML as a standard model of data exchange, XML functional dependencies (XFDs) have become important to areas such as key analysis, document normalization, and data integrity. XFDs are more complicated than relational functional dependencies because the set of XFDs satisfied by an XML document depends not only on the document values, but also the tree structure and corresponding DTD. In particular, constraints imposed by DTDs may alter the implications from a base set of XFDs, and may even be inconsistent with a set of XFDs. In this paper we examine the interaction between XFDs and DTDs. We present a sound and complete axiomatization for XFDs, both alone and in the presence of certain classes of DTDs; we show that these DTD classes induce an axiomatic hierarchy. We also give efficient implication algorithms for those classes of DTDs that do not use disjunction or nesting. © Springer-Verlag Berlin Heidelberg 2007.