The Evolving Algebra Semantics of Class and Role Hierarchies

G. Gottlob, M. Schrefl
Gott98a (1998)
B. Thalheim, L. Libkin (eds.): Semantics in Databases. Springer Verlag, Lecture Notes in Computer Science, LNCS Vol. 1358, pp. 92-113, ISBN 3-540-64199-8, 1998.
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The formal description of the semantics of object-oriented data models is still a heavily debated research problem. This paper shows how evolving algebras provide an elegant way to specify the operational semantics of object-oriented data models. In particular, we define the formal semantics of a novice feature of object-oriented data models proposed recently by different authors: role hierarchies. As opposed to traditional class hierarchies, role hierarchies allow objects to dynamically acquire multiple independent types.