XML Functional Dependency and Schema Normalization

Normalization theory is necessary for designing a good XML document. A good document means that it has minimal redundancy. The research on XML functional dependency and normalization is still an open problem. This paper first presents a path language of XML model, then proposes a new kind of XML functional dependency (XFD) that has stronger expression ability to XML functional dependency that can result in redundancies. In this paper, the problems of XFD logical implication and XFD closure are studied and a group of the corresponding inference rules is proposed. Based on the XFD, a kind of XML normal form (XNF) and an algorithm converting into XNF are also proposed in this paper.