The EE Systems Theory

The EE systems theory is about the behaviour, the construction and the operation of systems. Systems are classified into three regions: organised simplicity, organised complexity and unorganised complexity. The definition of a (homogeneous) system is presented as a triple (C, E, S), where C is a set of elements of some category, E is a set of elements of the same category as the elements in C and S is a set of interaction bonds among the elements in C and between them and the elements in E. Examples of categories are physical, biological and social. Organisations belong to the category of social systems. Three sorts of conceptual models are distinguished: black-boxes, grey-boxes and white-boxes. The well-known finite automaton or finite state machine and the discrete event system are examples of grey-boxes. For a thorough discussion of the grey-box and the white-box, the PRISMA model is introduced. In this meta model, systems are considered to be discrete event automata, operating in a linear time dimension. Its formalised ontological model is particularly suited to study organisations formally. In the PRISMA grey-box, three ways of mutual influencing between (the elements of) systems are distinguished, called activating, restricting and impeding. The PRISMA white-box allows one to conceive organisations as prismanets: networks of processors, channels and banks. Prismanets are comprehensive formalised systems, open to formal analysis and to implementation in software. They can conveniently be expressed in prismanet diagrams. To illustrate the PRISMA model, two example prismanets are presented: one regards a traffic control system and the other a car rental organisation. Next, the generic transaction prismanet is discussed. It is the understanding of the complete transaction pattern from the PSI theory in the PRISMA model. Lastly, the quality aspects of PRISMA models are discussed, as well as their importance for software engineering.