A class of functional dependencies for the nested relation database model

Functional dependencies in the nested relation database model faces two main problems. First, there is no agreement with respect to the fundamentals of functional dependencies. Second, the notation used to denote a dependency in the nested relation model is usually overwhelming and represents in many cases a barrier in this area. The cause of the paucity in this field seems to be the number of possible ways we have to reason about functional dependencies when we are dealing with schemata which is not described in a plain manner as in the relational model.; Some natural questions that one might raise about this situation are: what are the classes of nested functional dependencies (NFDs) that we can denote so that no drawbacks exist in terms of their semantics and manipulation? Is there any easy to follow notation that can be used to express such classes of NFDs and that can be easily seen as a natural extension of the relational model? If such notation exists then what is a suitable set of sound and complete inference rules for this notation? How can we solve its implication problem?; We address these questions proposing a new class of nested functional dependencies. First we classify the denotable NFDs under several perspectives separating those classes of NFDs that have good properties in terms of manipulation. Next, we propose a NFD notation that can denote those classes of NFDs. The proposed notation is defined so that it can be seen as an extension of the functional dependencies found in the flat relational model. This approach has the advantage that the theory developed for the relational model can be borrowed into the nested model without major complications. We discuss a set of inference rules for this notation proving their soundness and completeness. Finally, we also discuss algorithms to compute their closure and functional implication.