Conversely, general theories of, say, computational complexity can provide insights about many natural and human systems. Criticality and Complexity Criticality is a central theme in complexity. NLD concerns the behaviour of systems with non-linear terms and leads immediately to studies of chaos and related topics. Nonlinearity can arise in many ways, including interactions between objects. So NLD also encompasses systems that consist of many interacting elements.
Fractals arise in the context of the behaviour of iterative systems.
One link with nonlinear dynamics arises because determination of any systems involves iterative computation. GAs, introduced by John Holland, emulate evolution to provide very robust methods of search and optimization. The behavior of the cells is determined not only by its own internal state and program, but also by the states of the cells in some neighbourhood around it. It is now widely recognized that many computational problems cannot easily be solved directly. From Biological Systems to Artifical Life Artificial life is one of the most popular areas of complexity research.