Since Codd introduced the relational database model and functional dependencies [Codd 1970], the semantics of relationships between the attributes of a database has been extensively studied by many computer scientists. In this chapter we introduce an application of the calculus of binary relations to the (n-ary) relational database model. This consists of using the notion of difunctional relations to define difunctional dependencies in the relational database model. Difunctional dependencies are weaker than functional dependencies, but more regular than the other well-known dependencies.
KeywordsBinary Relation Functional Dependency Relational Schema Social Security Number Deterministic Relation
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