The GROOVE Simulator: A Tool for State Space Generation

The tool described here is the first part of a tool set called GROOVE (GRaphbased Object-Oriented VErification) for software model checking of objectoriented systems. The special feature of GROOVE, which sets it apart from other model checking approaches, is that it is based on graph transformations. It uses graphs to represent state snapshots; transitions arise from the application of graph production rules. This yields so-called Graph Transition Systems (GTS’s) as computational models. The simulator does a small part of the job of a model checker: it attempts to generate the full state space of a given graph grammar. This entails recursively computing and applying all enabled graph production rules at each state. Each newly generated state is compared to all known states up to isomorphism; matching states are merged, in the way proposed in [4]. No provisions are currently made for detecting or modelling infinite state spaces. Alternatively, one may choose to simulate productions manually. This paper describes two examples: Sect. 2 shows the behaviour of a circular buffer and Sect. 3 the concurrent invocation of a list append method. In both cases the behaviour is defined by a graph grammar, but to provide some intuition, Fig. 1 approximately describes the behaviour, using Java code. We conclude in Sect. 4 with a summary of tool design, implementation and planned future extensions.