Schema Equivalence as a Counting Problem
In this paper we introduce some terminology for comparing the expressiveness of conceptual data modeling techniques, such as ER, NIAM, PSM and ORM, that are finitely bounded by their underlying domains. Next we consider schema equivalence and discuss the effects of the sizes of the underlying domains.This leads to the introduction of the concept of finite equivalence, which may serve as a means to a better understanding of the fundamentals of modeling concepts (utility). We give some examples of finite equivalence and inequivalence in the context of ORM.
KeywordsConceptual Schema Object Type Fact Type Schema Equivalence Base Expressiveness
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