A Humble Tribute to 50 Years of Fuzzy Sets

2015 was the 50th anniversary of the first contribution on Fuzzy Sets 1 and from the International Journal of Computational Intelligence Systems we want to take this opportunity to pay tribute to Lofti Zadeh, the father of Fuzzy Sets theory, which has guided many researchers and resulted in important advances in various fields of modern society. We also recognise and thank all the researchers who have devoted their careers to studying, developing and applying Fuzzy Sets theory across these 50 years. We want to show our respect, admiration and appreciation to all of them. This Special Issue does not aim to simply be a comprehensive review of the history of Fuzzy Sets; rather, it intends to provide multiple views of these 50 years by incorporating contributions that either survey the use of Fuzzy Sets in different topics, or validate its application in real-world problems or its links with other theories. To achieve this, relevant and well-known researchers from the Fuzzy Sets and computational intelligence fields have contributed seven papers to this issue. The first paper, Where Fuzzy Set Theory Reached in its 50th Year: A Comprehensive Literature Review, co-authored by Cengiz Kahraman, Sezi Cevik Onar and Basar Oztaysi, shows the evolution of Fuzzy Sets theory across this 50-year history by first exploring the chronological evolution of publications related to fuzzy sets in diverse research areas and then recording the historical progress of ordinary fuzzy sets and their extensions. Lastly, the authors present a range of views on the future of fuzzy sets.