Systems engineering needs a formal basis

Today, more and more electronic parts of automobiles or aircrafts are realized as software, often distributed on a network of high-performance processors that are embedded in the car or airplane. In the systematic development of a distributed interactive system, we distinguish the following views: the interface view, the data view, the distribution view, and the process view. Each of these views is helpful and has its place in the development and design process of systems. We show how to formalize these different views by logical means. The development of a system is carried through several levels of abstraction. We also demonstrate how to formalize the typical steps in the development process. In particular we may identify three directions of development: refinement within one level of abstraction transition from one level of abstraction to another incremental development by enlarging the functionality. We introduce refinement relations to capture these three dimensions of the development space. We give verification conditions for these refinement steps. In this way, a logical basis for the development of systems is created.