Urban chaos and perplexing dynamics of urbanization

A city with fractal structure used to be thought of as a kind of spatial chaotic attractor. Several chaotic attractors indeed can be found by simulating urbanization dynamics through numerical iterations. However, the results lend little support to the suggestion that real cities are chaotic systems. The rural-urban population interaction model does not display chaotic behavior in normal state, but chaos will happen only if the parameter values of the model deviate from the reality. Accordingly, whether or not complex urban systems are chaotic is posed as a pending question. Varied simulation experiments based on the urbanization dynamics imply that the complex patterns of cities occur on the edge of chaos rather than in chaotic state. This result presents an angle of view for us to understand Holland's question, i.e., why the interactions that form a city are typically stable in the real world.