Evolving derived entity types in conceptual schemas in the UML

Ideally, the basis for the evolution of an information system is its conceptual schema. The evolution operations should be applied directly to the conceptual schema, and from here they should propagate automatically down to the database schema and application programs. In particular, the evolution of entity types has been studied extensively. However, very little attention has been paid to the evolution of their derivability (for example, changing from base to derived). Our contribution in this paper is an analysis of the evolution of entity types taking into account their derivability. We define a list of possible schema changes related to derivability and we specify them by giving its pre and postconditions. We deal with conceptual schemas in the UML/OCL, although our operations can be adapted to any conceptual modeling language.