Dealing with redundancies and dependencies in normalization of XML data

In this paper we discuss the problem of redundancies and data dependencies in XML data while an XML schema is to be normalized. Normalization is one of the main tasks in relational database design, where 3NF or BCNF, is to be reached. However, neither of them is ideal: 3NF preserves dependencies but may not always eliminate redundancies, BCNF on the contrary—always eliminates redundancies but may not preserve constraints. We discuss the possibility of achieving both redundancy-free and dependency preserving form of XML schema. We show how the XML normal form can be obtained for a class of XML schemas and a class of XML functional dependencies.