Function dependencies in XML

Functional dependency is an integral part in the normalization research on XML data base. To express the XML functional dependency which give rise to data redundancy, various complicated constraints on functional dependency are analyzed with a path language proposed on DTD basis to give stronger expression to the navigation and location for an XML document. With a set of XML schemes and representation to formalize documents presented, a kind of definition of XML functional dependency (XFD) is given. Comparing with the XFD defined previously, this definition of XFD can express more functional dependencies existing in XML and is available to generalize about the constrainabilities on the functional dependencies defined before by the expression of path.