The main body of a chapter is a stepwise development of the Mathematica program. At the end of a chapter, the authors suggest some simulation projects for the reader. The common structure of almost all the models is that individuals move about on a checkerboard and interact when facing one another. Interaction may consist in influencing each others beliefs, attitudes and opinions or in playing games, especially Prisoner's Dilemma games, which have somehow become the E. coli of interaction studies for many social scientists. Chapter 1 introduces the basics of the model.
Individuals move about simultaneously on a two dimensional rectangular grid.
Not all sites are occupied. Moving is local and permitted only to empty adjacent cells in the north, south, east or west. Since simultaneous moves may cause collisions, a set of rules is worked out which prevent individuals from moving onto the same site. These are used to identify impending collisions and then change randomly to avoid deadlocks. Interaction is again local and takes place within a certain neighbourhood.