Linguistic Variables

Abstract

Linguistic variables [Zad75a], [Zad75b], [Zad75c] are variables that take linguistic terms as their values. The linguistic variable can be used as a quantitative extension of the quantity space representation for continuous parameters used in QP theory, and it can be used to reduce ambiguity stemming from all of the sources within QP theory identified earlier. Linguistic variables permit us to say that the moisture content of the shale is low, instead of merely saying that it is > 0, as QP theory would provide, or 21.2%, as an overprecise numerical theory might require. In addition, linguistic variables provide a natural representational mechanism for other kinds of soft, semiquantitative information, such as characterizations of partial functional relationships between parameters. In the remainder of this section we describe further the concept of a linguistic variable.