Complex Adaptive Systems: An Introduction to Computational Models of Social Life (Princeton Studies in Complexity Book 14)

by John H. Miller

In chapter 9 we explore a model of sand piles in which we randomly drop grains of sand onto a table. A pile forms as the sand falls, and eventually grains begin to run off the edges of the table in avalanches of various sizes. The distribution of avalanche sizes follows a power law that implies behavior that is quite different from that arising from a normal distribution. Agent intention can also alter the patterns that emerge in complex systems. In the case of the Sand Pile model, if we give the falling grains of sand a bit of control on where they land and some desires (like maximizing the size of the resulting avalanche), the system is no longer governed by a power law and instead enters a bizarre periodic cycle.