The Tracta Approach for Behaviour

The need for modularity in the behaviour analysis of concurrent systems has been answered successfully by making reachability analysis compositional. Compositional reachability analysis (CRA) on the other hand, often exacerbates the state explosion problem; subsystem analysis leaves out information from the subsystem environment (context), which could considerably reduce the number of states allowed into its behaviour state-graph. To deal with that, we have chosen to incorporate context constraints in CRA. In the Tracta approach developed in our section, context constraints are expressed as processes in our model (we call them interface processes), that are composed with the subsystem, without aaecting the global system behaviour. Tracta supports both automatically generated and user-speciied interfaces. It also provides an elegant way of checking violation of safety properties by the system under analysis. This work, besides introducing the main open problems in this area of research, is a detailed presentation of Tracta and its underlying theory, in their current form.