A fuzzy rule is defined as a conditional statement in the form:

IF x is A

THEN y is B

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.

Comparison between Boolean and fuzzy logic rules

A classical IF-THEN statement uses binary logic, for instance:

IF man_height is > 180cm

THEN man_weight is > 50kg

Comparison between computational verb and fuzzy logic rules

Computational verb rules(verb rules, for short) are expressed in computational verb logic. The difference between verb and fuzzy rules is that the former using verbs other than BE in the statement while the latter using verb BE only. For example, the two fuzzy rules in above have the following corresponding computational verb counterparts:

• IF man_height becomes tall THEN man_weight become heavy;
• IF man_height increase to tall THEN man_weight probably grow to heavy;
• IF man_height stays tall THEN man_weight could remain heavy;