Economists traditionally tackle normative problems by computing optimal policy, i.e. the one that maximizes a social welfare function. In practice, however, a succession of marginal changes to a limited number of policy instruments are implemented, until no further improvement is feasible. I...

Migration becomes a more and more significant process that triggers various types of complex behavior. After analyzing the process, especially with regard to the occurrence of nonlinear behavior, a model is build to include the features that may lead to the occurrence of cycles of migration...