Abstract. Much research has been done in the field of model-checking complex systems (either hardware or software). Approaches that use explicit state modelling mostly use bit vectors to represent the states of such systems. Unfortunately, that kind of representation does not extend smoothly to systems in which the states contain values from a domain other than primitive types, such as reference values commonly used in object-oriented systems. In this paper we report preliminary results on applying CTL model checking on state spaces generated using graph transformations. The states of such state spaces have an internal graph structure which makes it possible to represent complex system states without the need to know the exact structure beforehand as when using bit vectors. 1

Proceedings of the Eighth Workshop on

In this paper we specify an operational run-time semantics of Assignment Featherweight Java — a minimal subset of Java with assignments — with around advice, using graph transformations. We introduce a notion of correctness of our specification with respect to an existing semantics and claim a number of advantages over traditional mathematical notations, that come forth from the executable nature of graph-transformation-based semantics. Using test programs as graphs during specification of the semantics, simulation can help in verifying the correctness of the rules simply by testing, increasing the rigorousness of the specification process. Also, execution of the semantics results in a state space that can be used for analysis and verification, giving rise to an effective method for aspect program verification. As a criterion for correctness, we use a structural operational semantics of this language from the so-called Common Aspect

Abstract. Refactoring of information systems is hard, for two reasons. On the one hand, large databases exist which have to be adjusted. On the other hand, many programs access that data. These programs all have to be migrated in a consistent manner such that their semantics does not change. It cannot be relied upon, however, that no running processes exist during such a migration. Consequently, a refactoring of an information system needs to take care of the migration of data, programs, and processes. This paper introduces a model for complete object-oriented systems, describing the schema level with classes, associations, operations, and inheritance as well as the instance level with objects, links, methods, and messages. Methods are expressed by special double-pushout graph transformations. Homomorphisms are used for the typing of the instance level as well as for the description of refactorings which specify the addition, folding, and unfolding of schema elements. Finally, a categorial framework is presented which allows to derive instance migrations from schema transformations in such a way that programs and processes to the old schema are correctly migrated into programs and processes to the new schema. 1

Conceptual modeling is the field where humans model natural or artificial systems. The basic requirements of a model is for it to be both easy to understand and to describe correctly and unambiguously the system that it is modeling. Although these goals are trivial, over time most modeling methodologies have been able to satisfy only one of the requirements fully, regularly the ease to understand, while leaving the correctness and ambiguousness problems aside. There exist some formal modeling languages but a full model is fairly complicated to understand in these languages. OPM is an holistic system modeling methodology that combines all of the aspects of a system in one model, and at the same time provides mechanisms to manage the complexity of the model with zooming and folding operations, which divide the complexity of a large system into many models that are interconnected. Although the basic syntax and semantics of an OPM system model are already defined, this definitions is not complete and leaves room for incorrect models and models that can be interpreted in different ways. This work advances de formal definition of OPM by providing a graph grammar which creates OPM diagrams whose syntax is correct when a pair of interconnected things are taken, but the correctness of the whole diagram is not assured. After that a diagram is created, a validation methodology must be applied to the diagram to assure that it is fully semantically and syntactically correct. The validation methodology is also based on graph grammars.