On hearing of the award, Zadeh remarked that it meant a lot to him for several reasons: “First, because fuzzy logic has been somewhat controversial. Some people have greeted it with enthusiasm but others have been skeptical. It also has a special significance for me because I am a great admirer of Spain and the Spanish people. I’d therefore like to take this opportunity to express my deep appreciation to all those who were involved in my receiving this award, particularly Luis Magdalena and Enric Trillas of the European Centre for Soft Computing in Mieres, who were among those putting forward my nomination.

Classical logic, based on class membership, imposes that an element should strictly belong ir not belong to a clearly demarcated set, like for instance the set of even numbers. But reality is a lot more complex. Hence we have groups, classes and sets whose boundaries are blurred, like that of “good basketball players.” To belong to this set, a basketball player must “be tall” and “shoot well”, but these concepts are imprecise. A binary system would specify, for example, that “be tall” equates to “measure more than 185 cm” and discard all players below this height, regardless of their shooting prowess.

But fuzzy logic, like a human coach, would find room in the set of good players for one who measures 184 cm but is an excellent shooter. In this sense, what fuzzy logic does is bridge the gap between classical logic and the real world.

This indeed is what Zadeh was seeking when the began the research that led him to fuzzy logic: “As an engineer, I was always convinced that mathematics held the answers to almost any problem, but I also realized that classical mathematics was constrained by its inability to tolerate imprecision.” To get over this shortcoming, Zadeh turned to the human model: “We humans have a remarkable capability to reason and make decisions in an environment of uncertainty and incompleteness of information (…). The principal objective of fuzzy logic is the formalization of this capability.”

Human beings intuitively apply fuzzy logic to their decisions, juggling imprecise data and weighing up each relevant element. Zadeh’s contribution was to apply such logic to the decision-making processes of systems and computers, so they cease to operate as mere calculating machines and become capable of evaluating degrees and shades of reality and deciding accordingly in an autonomous or semi-autonomous fashion (with little or no human intervention).

According to the jury, the contributions of Lotfi A. Zadeh (Baku, Azerbaijan, 1921) have been “enthusiastically adopted by industry, where thousands of engineers have designed a whole plethora of complex and intelligent systems (…). With several tens of thousands of patents worldwide, fuzzy control is now an essential component in a wide range of consumer products, including video cameras, washing machines and medical instruments, as well as in more complex systems such as automatic trains, wastewater treatment plants, and intelligent control of car engines.”

A seminal paper

En 1965, Lotfi Zadeh articulated fuzzy sets for the first time in a paper that would come to be among the most cited of the 20th century, with over 35,000 mentions. And the next step from there was the development of fuzzy logic, a brilliant contribution to extending the frontiers of knowledge. Indeed Zadeh is defined in the jury’s citation as the founder of “a new field of research which has proved powerful in many application domains.”

The controversy around fuzzy logic began with the name: “The word fuzzy has a pejorative connotation in English, and this turned out to be a handicap when it came to gaining the acceptance of the scientific community. But it was the word that came closest to what I had in mind. In Asia, however, they don’t have problems with the word fuzzy, so they were more receptive to my work. They also have a culture that accepts shades of grey, as opposed to the western – Cartesian – tradition where everything is either black or white.”

This was perhaps the reason, he speculates, that one of the earliest applications of his concept was the automated subway system in the Japanese city of Sendai. The application of fuzzy logic to the network’s control system enabled trains to change speeds as if they had an experienced human driver at the wheel. Indeed acceleration and braking were more even with the new system, resulting in less electricity consumption as well as a smoother ride for passengers.

Fuzzy logic opened the door to machine understanding of such imprecise instructions as “brake smoothly” or “refrigerate until the air is cool,” which would be instantly understood by any human being acquainted with the system, but is utterly impenetrable for a conventional computer program. The conceptual shift was so abrupt that Zadeh initially had to face the skepticism of many scientist colleagues, until the success of the practical applications of his theory dissipated all such doubts.

Zadeh’s work has enabled us to communicate with machines through an increasingly natural, human language. In the words of jury secretary, Ramón López de Mántaras: “Rather than human beings having to take the time to learn the complex mathematical language of machines, fuzzy logic proposes a simpler language, so it is the machines that mimic human patterns of reasoning and behavior in order to solve problems.”

The laureate, still working at the age of 91, sees this as the most promising research avenue in the fuzzy logic field, and hopes to author some further advance that will connect computers and systems more closely with natural language.

International jury

The jury in this category was chaired by George Gottlob, Professor of Computer Science at the University of Oxford (United Kingdom), with Ramón López de Mántaras, Director of the Artificial Intelligence Research Institute of the Spanish National Research Council (CSIC) acting as secretary. Remaining members were Oussama Khatib, Professor in the Artificial Intelligence Laboratory in the Computer Sciences Department of Stanford University (United States), Rudolf Kruse, Head of the Department of Knowledge Processing and Language Engineering at Otto-von-Guerike-Universität Magdeburg (Germany), Mateo Varelo, Director of the Barcelona Supercomputing Center (Spain) and Joos Vandewalle, Head of the SDC Division in the Department of Electrical Engineering at the Katholieke Universiteit Leuven (Belgium).