International Encyclopedia of Systems and Cybernetics

The ordering of a number of elements, relations or systems according to some pre-defined characteristics.

Classification is basic for the organization of information into frameworks and the typification of systems. It is however a difficult subject.

M. MARUYAMA clarifies some important points:

"… the classificational universe is characterized by its being divided into categories and subcategories… The structure of this universe is hierarchical. The relations are conceived in terms of the kinship in the hierarchy of superdivisions and subdivisions" (1966, p.55).

Classifications tend thus to be ordered in hierarchical "trees", which supposes criteria… not necessarily accepted by all concerned people, because they are selected "ad-hoc" by the classificator.

Moreover R. SOKAL showed that different ways of clustering the elements, when all are endowed with characteristics of various types, lead easily to the possibility of alternative classifications (1974).

Another significant aspect observed by MARUYAMA is that: "The relations are static" (Ibid.).

Classifications are more structure-oriented than process-oriented.

However, "Classifications may be polycriterial, i. e., several classifications using mutually independent criteria may be surimposed" (Ibid., p.56), as for example, listing people by age and, otherwise, by alphabetic order of names, or birth place. Each specific criterion produces a selected set, but the different sets present intersections, which can be tabulated or otherwise studied. For such purposes, multi-dimensional matrixes or fractalized VENN diagrams can be constructed (A. EDWARDS, 1989).