ABSTRACT
Time and Change: An Introduction to Basic Concepts Previous chapters, especially Chapter 7, have discussed the concept of similarities and differences. In this chapter we look at the temporal aspects of these concepts. One way to think about this chapter is that the time dimension of the model space is a temporal specialization of similarities and differences. We think of similarity across time as stability, and differences or variability across time as change. A bridge between the two is that invariants represent what is common and stable, and variants represent what differs and changes. If everything were stable, then time could be abstracted away, and we would not need to include this chapter, or the time dimension in the model space. However, change is ubiquitous; that is, it is everywhere and it is continual — in the natural world and the engineering world. erefore, change is the aspect of time that motivates and dominates this chapter.
