Complex systems models are idealized and structured representations of a complex, holistic system in which many simple components are interacting in a nonlinear way according to simple, fundamental rules, with a potential to generate unexpected order. Because higher-level patterns of environmental systems and human society across time and space emerge from localized interactive processes occurring at lower levels, these systems have been regarded as typical examples of so-called complex adaptive systems (CAS). As such, attempts to model the principle and behavior of CAS have received increasing attention among geographers.