An ontological analysis of the relationship construct in conceptual modeling

Conceptual models or semantic data models were developed to capture the mea ning of an application domain as perceived by someone. Moreover, concepts e mployed in semantic data models have recently been adopted in object-orient ed approaches to systems analysis and design. To employ conceptual modeling constructs effectively, their meanings have t o be defined rigorously, often, however, rigorous definitions of these cons tructs are missing. This situation occurs especially in the case of the rel ationship construct. Empirical evidence shows that use of relationships is often problematical as a way of communicating the meaning of an application domain. For example, users of conceptual modeling methodologies are freque ntly confused about whether to show an association between things via a rel ationship, an entity, or an attribute. Because conceptual models are intended to capture knowledge about a real-wo rld domain, we take the view that the meaning of modeling constructs should be sought in models of reality. Accordingly, we use ontology, which is the branch of philosophy dealing with models of reality, to analyze the meanin g of common conceptual modeling constructs. Our analysis provides a precise definition of several conceptual modeling c onstructs. Based on our analysis, we derive rules for the use of relationsh ips in entity-relationship conceptual modeling. Moreover, we show how the r ules resolve ambiguities that exist in current practice and how they can en rich the capacity of an entity-relationship conceptual model to capture kno wledge about an application domain.