The application of fuzzy logic to continuous process-control problems. As an alternative to classical mathematical control techniques, a rule-based controller can be built using rules like ‘ if the temperature is fairly high, then slightly reduce the flow’. The adjectives are converted into fuzzy variables, which are used in a fuzzy-logic algorithm to produce the control outputs. Such rules are captured from expert human controllers by knowledge acquisition techniques. Some fuzzy controllers have reported performance at least as good as human operators.