Compatibility measures using fuzzy truth and co-implication

A compatibility measure is a scaler measure that assesses some type of agreement between two fuzzy sets. The three general classes of compatibility measures are set theoretic, metric, and logic. Set theoretic compatibility measures are the ones predominantly found in the literature. Recently, however, metric and logic compatibility measures are being used. The logic class of compatibility measures and its two different motivating influences, fuzzy truth and co-implication, are described. Applying fuzzy logic in rule-based expert systems provides the framework for employing fuzzy truth as a compatibility function. The co-implication approach is shown to produce similarity relations between degrees of membership