This chapter provides a general introduction to the concept of system of systems (SoS), their definition, the position of the concept within related concepts, the relationship of modeling and simulation issues to SoS, and the relationship of modeling and simulation to the development of SoS. Section 2.2 of Chapter 2 defines SoS and a number of related concepts and pays particular attention to the concept of emergent properties and its role in understanding both SoS and models of systems. Section 2.3 reviews a number of important examples of SoS, which will be explored in depth with respect to modeling and simulation later in the book. Section 2.4 takes up modeling issues particularly associated with SoS. Section 2.5 relates the modeling issues to the structure of architecture description documents (ADD) and distinguishing architecture as a concept or as decision from architecture as modeling artifacts.
Five key lessons come from the discussion: