In a concetpual schema that includes specializations and generalizations, and that allows multiple classification, an entity may be, at a given time, instance of one or more entity types. We call type configuration of an entity the set of entity types of which it is instance at some time. In this paper, we characterize the set of valid type configurations, taking into account the constraints defined by specializations and generalizations. We also analyze the poblem of determining the valid evolution of the type configuration of entities in the context of IsA hierarchies. We dexeribe the temporal features of entity types and the evolution constraints that influence entity evolution. In particular, we propose and define the specailization evolution constraints, which extend the classical distinction between static and dynamic entity types. Taking into account all these features and constraints, we characterize the set of valid type configuration transitions. In both cases, we tackle the problem for the general class of conceptual schemas, allowing multiple specialization, generalization and classification, as well as dynamic classification.
展开▼
