Fuzzy-set based logics - An history-oriented presentation of their main developments
Résumé
The representation of human-originated information and the formalization of com-monsense reasoning has motivated different schools of research in Artificial orComputational Intelligence in the second half of the 20th century. This new trendhas also put formal logic, originally developed in connection with the foundationsof mathematics, in a completely new perspective, as a tool for processing informa-tion on computers. Logic has traditionally put emphasis on symbolic processingat the syntactical level and binary truth-values at the semantical level. The ideaof fuzzy sets introduced in the early sixties[Zadeh, 1965]and the development offuzzy logic later on[Zadeh, 1975a]has brought forward a new formal frameworkfor capturing graded imprecision in information representation and reasoning de-vices. Indeed, fuzzy sets membership grades can be interpreted in various wayswhich play a role in human reasoning, such as levels of intensity, similarity degrees,levels of uncertainty, and degrees of preference.