A fuzzy rule is defined as a conditional statement in the form:
where x and y are linguistic variables; A and B are linguistic values determined by fuzzy sets on the universe of discourse X and Y, respectively.
A classical IFTHEN statement uses binary logic, for instance:
Classical rules are expressed in Boolean logic. On the other hand, fuzzy rules are multivalued. In fuzzy rules, the universe of discourse of the variable man_height is a fuzzy set (tall, medium, short). For example:
