Abstract

The nature and functions of classifications are first discussed and the differences between natural and artificial classifications are explicated. It is shown that borderline-case type problems result not from classifications, but from extending them to wider domains. Some methods of solving such problems are considered. The differences between monothetic and polythetic classifications are also taken up. A new treatment of trees as relations and their levels is developed. Certain kinds of hierarchies such as the classificatory, the inclusional, and the structural are then characterized by means of the tree concept