Parameterized specification and verification of the Chilean electronic invoices system

We present the complete process of a formal specification and verification of the Chilean electronic invoice system which has been defined by the tax agency. We use this case study as a real-world and real-size example to illustrate our methodology for specification and verification of distributed applications. Our approach is based on a new hierarchical and parameterized model for synchronised networks of labelled transition systems. In this case study, we use a subset of the model as a graphical specification language. We check this formal specification of the invoice system against its informal requirements, described in terms of parameterized temporal logic formulas. Their satisfiability cannot be checked directly on the parameterized model: we introduce a method and a tool to instantiate the parameterized models and properties, allowing to use standard (finite-state, bisimulation-based) model-checkers for the verification. We also illustrate the use of different methods to avoid the state explosion problem by taking advantage of the parameterized structure and instantiations.