Multivalued Dependency and Normal Form for XML Documents

Abstract

In this article we address the problem how to normalize document structure using DTD in XML documents. First, we discuss the redundancy problem that cannot be eliminated by normal forms based on functional dependencies in XML. Next, we propose new dependency, multivalued dependency in XML, like in relational databases and describe some properties in functional and multivalued dependencies. We also propose new normal form (4XNF) based on multivalued dependency in XML documents and then discuss the relationships between 4XNF and other normal forms (XNF, 4NF in flat relations and NNF in nested relations). Finally, we present an approach for converting any DTD into it in 4XNF by using multivalued dependencies.