a logic-based knowledge representation scheme founded on the axiom that set membership is based on a probability distribution (as opposed to traditional set theory, in which an element is either in a set or not in that set). An example of fuzzy logic is that a certain person can be a member of the set of tall people with 75% confidence and also be a member of the set of short people with 5% confidence. Fuzzy logic also breaks the assumption of the excluded middle in philosophy, in that an element can be a member of both a set and the opposite of that set at the same time. Fuzzy logic is often used to support the design of expert systems as well as to control algorithms. [first proposed in 1965 by Romanian-born computer engineer Lotfi A. Zadeh (1921– )]