“The ability to map between levels of description, and in particular the understanding of when a shift from a higher-level to a more detailed description is needed to achieve a desired degree of accuracy, is fundamental to an effective theory in any field.”— Ron Sun, L. Andrew Coward, cogsci.rpi.edu
“Standard examples of level hierarchies, some of which are also inclusion hierarchies, are: physico-chemical ( e.g. elementary particles –atoms – molecules); biological (e.g. cells – organs – individuals – species); economic (individuals – working groups or departments – firms – national economies);…”— David Lane, insiteproject.org
“I distinguish four different kinds of hierarchy: order hierarchy, inclusion hierarchy, control hierarchy and level hierarchy.”— David Lane, insiteproject.org