title: Levels of description: a novel approach to dynamical hierarchies.
abstract: We present a novel formal interpretation of dynamical hierarchies based on information theory, in which each level is a near-state-determined system, and levels are related to one another in a partial ordering. This reformulation moves away from previous definitions, which have considered unique hierarchies of structures or objects arranged in aggregates. Instead, we consider hierarchies of dynamical systems: these are more suited to describing living systems, which are not mere aggregates, but organizations. Transformations from lower to higher levels in a hierarchy are redescriptions that lose information. There are two criteria for partial ordering. One is a state-dependence criterion enforcing predictability within a level. The second is a distinctness criterion enforcing the idea that the higher-level description must do more than just throw information away. We hope this will be a useful tool for empirical studies of both computational and physical dynamical hierarchies.
authors.affiliation: Centre for Research in Cognitive Science, University of Sussex, UK. sm66@cogs.susx.ac.uk
authors.forename: Simon
authors.initials: S
authors.lastname: McGregor
authors.forename: Chrisantha
authors.initials: C
authors.lastname: Fernando
mesh_terms: D007257:Information Theory; D008962:Models, Theoretical