ABSTRACT
Fuzzy set theory was initiated by L. A. Zadeh with his seminal papers (Zadeh 1965, 1968) in the 1960s. It was introduced as a means of modeling and representing with a precise mathematical theory imprecise uncertainties of the class of real-world objects. This new concept allows one to express imprecise and qualitative information in a precise and quantitative way. One good example of applying fuzzy set theory is to formulate human knowledge, often in the form of natural language, in a systematic and mathematically rigorous manner.
