Deriving and using descriptions of purpose

A language called Ted for representing teleological descriptions and a design method in which these descriptions can be captured and subsequently used for design reuse are described. The language is independent of any particular structure or behavior description language, but it builds on generalizations of such languages. Ted expresses the purpose of a component or activity in terms of behaviors prevented, guaranteed, or introduced by the component or activity. Given representation and acquisition schemes, system builders call use descriptions of purpose in explanation, diagnostic, and design systems. They can also use these descriptions to reuse designs and to diagnose the designed artifact in the future.<>