Empowering model repair: A rule-based approach to graph repair without side effects

Working with models can lead to inconsistencies due to erroneous or contradictory actions during concurrent modeling processes. Modern modeling environments typically tolerate inconsistencies and support their detection. However, at a later stage of development, models are expected to be consistent, which means that their inconsistencies should be considered and resolved. The process of resolving model inconsistencies is usually referred to as model repair. Our approach to model repair is semi-automatic in the sense that the system computes appropriate paths for repair and the modeler decides which path to go. What is special about our approach is that the repair process can register every small improvement in the model. This allows the interaction with the user to be optimized, resulting in an approach with a high level of automation on the one hand and flexible configuration options on the other. The approach is able to provide all possible repair plans that do not have side effects, i.e., the computed repair plans do not inadvertently introduce a new inconsistency into the model so that a consistent model cannot be achieved after the repair. Since models often have a graph-like structure, we present our approach to model repair based on graphs. Our approach is completely formal and uses the algebraic graph transformation approach to show its correctness.