An Astral specification for a railroad controller

It is generally accepted that development of requirement models for real-time systems beneets from formal speciications. In order to be able to evaluate notations for use in the development of real-time software systems, we are performing a comparative review of some selected speciication notations. The study emphasizes the use of the notations in the domain of real-time (control) applications. Our review will be based on a speciication from a simple railroad controller model. This case contains data modelling aspects, functional aspects as well as temporal aspects. A (toy) railroad with a computer interface, is available in our laboratory, used for lab assignments. Typical elements to consider are usability with regard to the specii-cation in relation to the requirements, and second, usability with respect to further program development. This report discusses the problem as well as a model speciication, written in Astral. It also discusses ve-riication issues using the proof assistant PVS (Prototype Veriication System).