Editorial Forty years of fuzzy sets

International audienceThe first officially published paper on fuzzy set theory appeared in 1965. Since then, an enormous amount of literature spread out from this seminal paper of Lotfi Zadeh, as witnessed by the foundation of the journal Fuzzy Sets and Systems in 1978, and the growth in size of this journal from a small format set of rather thin four yearly issues, to the present 24 issues a year having between 150 and 200 pages each. The launching, in the 90s, of specific IEEE transactions specifically devoted to fuzzy systems, is also a major sign of the maturity of a novel area devoted to the representation and the processing of concepts that are intrinsically gradual. Since then most major publishers do propose a journal devoted to fuzzy sets and related notions. As a consequence it was felt important to celebrate the 40th anniversary of the paper “Fuzzy Sets”, to ask members of the board to write position papers discussing the role and future prospects of fuzzy sets in their area. Finally we could gather 14 contributions of various length, which is a small number compared to the actual list of topics where fuzzy set research is active. But it is also representative of the most recent trends