Functional Dependencies in the Higher-Order Entity-Relationship Model
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In this report we study the axiomatisation of functional dependencies in the Higher-Order Entity-Relationship Model (HERM).
Functional dependencies are considered to be an important class of dependencies. For this reason this class of dependencies has been well studied in the Relational Database Model (RDM). The axiomatisability of functional dependencies in the RDM has been shown by W. W. Armstrong.
In this report the axiomatisability will be carried over to the conceptual data models. For our purpose we choose the HERM as it is a well-founded conceptual data model. First, we consider the structure of the subattributes in the HERM and identify it as a Heyting algebra. Finally, we show the axiomatisation of functional dependencies in the HERM. This gives the basis for the solution of the implication problem in the HREM.
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