Abstract:

The concept of functional dependencies plays an important role in database theory since it is the basis of normal forms that are used to produce welldesign schema. Due to the complexity of the semistructured XML model, it is a challenge to define the functional dependencies and study the nature of those dependencies such as their capability of representation, logical implication and corresponding normal forms. The previous works in this area are surveyed and the approaches they deployed are described. Particularly, the paper focus on the comparison of functional dependencies definitions, the problem of logical implication and the discovery of dependencies. At last, some novel problems referring to dependencies such as relationship between value and type in shortly are discussed.

Key words: XML;functional dependencies;logical implication；dependencies discovery