Model evolution and system evolution

In this paper we define an evolution mechanism with formal semantics using the metamodeling methodology [Geisler et al.98] based on dynamic logic. A remarkable feature of the metamodeling methodology is the ability to define the relation of intentional and extensional entities within one level, allowing not only for the description of structural relations among the modeling entities, but also for a formal definition of structural\nconstraints and dynamic semantics of the modeled entities. While dynamic semantics on the extensional level means run-time behavior, dynamic semantics on intentional level describes model evolution in the system life cycle