Modeling: Is It Turning Informal into Formal?

Abstract

This work studies the meaning of the qualifier « semi-formal », which is usually attributed to design diagrams. Starting with a UML diagram as an example, the paper deals with the three modes of expressing things about the outside world: symbols, indexes and icons. The idea that the informational process consists in formalizing an informal given is discussed with regard to the supposed informal nature of the users’ requirements. It is also shown that a modeling language such as UML, although formalized in its inner constructions, can not strictly formalize the connection to the outside world it intends to model. This framework, arising from C. S. Peirce’s semiotics, allows to account for the modeling process as a effective interpretation reasoning on diagrams which are themselves made of signs. Thus we go beyond the apparent contradiction between the formal and the informal, using the concept of Interpretant. We can then envisage the study of design reasoning as dialogs between a model, its interpretants and the outside world or domain.