How to choose a suitable detail level describing a complex system.

Analyzing complex systems, the question occurs what one needs to know at the detail level in order to understand the dynamics at the system level. Ideally, one could use a higher level of description at which the system dynamics unfolds autonomously. That means once the initial state is known, one no longer needs to check the details at the lower level in order to predict the system. Formal methods have been developed to analyze the issues involved. In particular, the question of the flow of information between levels has been linked to the question of memory effects at the respective levels.