Fact Orientation in Complex Object Role Modelling Techniques.
Arthur H. M. ter Hofstede, Theo P. van der Weide · 1994
A number of proposals have been made to extend conventional data modelling techniques with concepts for modelling complex object structures, such as power types, sequence types and schema types. A drawback of the introduction of such new concepts is that the original simplicity of a single populatable concept is lost. In this paper we will show how a new kind of constraint, the extensional uniqueness constraint, can overcome this problem. Another advantage of this constraint is that it enables a less rigid identification schema. The usefulness of this new constraint is demonstrated in some concrete modelling situations. 1 Introduction Nowadays it is commonly accepted that information systems are best specified at the conceptual level first. Usually, two perspectives are distinguished at the conceptual level, the data and the process perspective. Many approaches to conceptual modelling of the data perspective exist. A well established class of conceptual data modelling techniques are t...