LOTFI A. ZADEH (1921-2017)

BY RUZENA BAJCSY

LOTFI ASKER ZADEH was born Feb. 4, 1921, in Baku, Azerbaijan, to Rahim Aleskerzade and Fanya Korenman. His father worked as a foreign correspondent for Iran’s leading newspaper, and his mother was a Russian physician.

Lotfi described his family as “well-to-do” in Baku and his early life and schooling there as excellent. Due to changes in the Soviet Union, the family moved to Tehran in 1931. By then, Lotfi had already developed a strong interest in engineering and was prepared to compete for admission to the prestigious engineering program at the University of Tehran. There, he met his future wife, then known as Fania—later identified as Fay on all formal records after their marriage in 1946. He earned a bachelor’s degree in electrical engineering in 1942, graduating into a world at war. At the time, Iran was occupied by Allied troops. Lotfi took practical work in construction, which confirmed his desire to further his education and pursue work at the frontiers of knowledge. He later emigrated to the United States and was admitted to the Massachusetts Institute of Technology (MIT), enrolling as a master’s candidate in 1944. At MIT, he conducted research with Ernst Guillemin, whom he described as an inspirational teacher and a key influence who encouraged him to pursue a doctorate. Lotfi ultimately decided to enroll at Columbia University in New York, as his parents had relocated there from Iran. He began doctoral studies in 1946 under John Ragazzini and earned his Ph.D. in 1949. That same year, he was invited to join the electrical engineering faculty at Columbia.

In the retrospective, Lotfi describes his two decisively positive events in his life: his move to New York to continue his studies and his decision to marry Fay. Their marriage lasted until 2017, when Fay died several months before him. Fay, a beautiful and gracious woman, was honored by Lotfi through a life-sized oil portrait he commissioned and later donated to The Faculty Club at the University of California, Berkeley. The portrait remains on public display. Lotfi was also an avid photographer throughout his life, specializing in portraits of accomplished engineers, scientists, and educators. His photo displays, often mounted in The Faculty Club, were a favorite among visitors to the historical Berkeley campus landmark.

Lotfi died Sept. 6, 2017, at the age of 96. He and Fay had two children: a daughter Stella, who died in 2006, and a son Norman, who survives him and has since changed the spelling of his surname to Zada.

Obituary, New York Times. This part was published in 2017 and written in part by his colleagues Stuart Russell (NAE 2025), Pravin Varaiya (NAE 1999), and Richard Muller (NAE 1992).

In 1949, he co-authored a research paper with Ragazzini that introduced what is now known as the z-transform method, which remains widely used in digital signal processing systems. He was promoted to a full professor at Columbia in 1957. Two years later, he joined the University of California, Berkeley, as a professor in the Department of Electrical Engineering. Over the course of 58 years on the Berkeley faculty, he achieved global recognition for his research and leadership. Throughout his career, Lotfi remained focused on building a strong educational structure alongside producing innovative research. In 1963, he became chair of Berkeley’s electrical engineering department and devoted substantial efforts to strengthen and expand computer science. When he stepped down as chair in 1968, the department had evolved into the Department of Electrical Engineering and Computer Sciences (EECS), positioning Berkeley as a rising leader in the computer sciences.

In 1973, Lotfi received the Institute of Electrical and Electronics Engineers (IEEE) Education Award, in recognition of his leadership as department chair and his broader contributions to engineering education. He also served UC Berkeley in multiple Academic Senate roles including on the Committee on Academic Planning and Resource Allocation (1992–95); the Committee on Committees (1969–70; 1980–81); the Committee on Courses of Instruction (1975–80); and the Committee on Faculty Awards (1990–92). Lotfi advised more than 50 Ph.D. students, many of whom became prominent figures in engineering, management, and the information sciences.

While on the faculty at Columbia University, he served as a visiting member of the Institute for Advanced Study in Princeton, New Jersey, in 1956. He also held several other visiting appointments, including professorships in electrical engineering at MIT in 1962 and 1968; visiting scientist appointments at IBM’s research laboratory in San Jose, California, in 1968, 1973, and 1977; a visiting scholar position at the Artificial Intelligence (AI) Center at SRI International in 1981; and another at the Center for the Study of Language and Information at Stanford University from 1987 to 1988.

Until 1965, Lotfi’s work focused primarily on system theory and decision analysis. That year, however, his research veered in a new direction, which he introduced in a paper titled “Fuzzy Sets,” published in the journal Information and Control.  The paper defined a novel approach to handling information and outlined the basic principles for applying these concepts in engineering decision-making. “Fuzzy Sets” quickly attracted widespread attention and became one of the most cited papers in the history of the information sciences. As of September 29, 2017, it had received more than 71,000 citations on Google Scholar. In its abstract, Lotfi wrote:

A fuzzy set is a class of objects with a continuum of grades of membership. Such a set is characterized by a membership (characteristic) function which assigns to each object a grade of membership ranging between zero and one. The notions of inclusion, union, intersection, complement, relation, convexity, etc., are extended to such sets, and various properties of these notions in the context of fuzzy sets are established.

His fuzzy-set research had wide-ranging applications, including AI, linguistics, logic, decision analysis, control theory, expert systems, and neural networks. From the outset, he anticipated that the concept would have its detractors, many of whom challenged its foundational premise. What is undisputed, however, is the tremendous impact his work had on real-world engineering applications. On the academic side, Google Scholar lists hundreds of thousands of papers with “fuzzy” in the title, and more than 20 journals are devoted exclusively to the field. On the industrial side, the U.S. patent database lists more than 33,000 patents and applications referencing “fuzzy” in the title. Fielded applications number in the tens of thousands and include systems for camera-focusing, automatic transmission gear selection, automated train controls, oil refineries, and nuclear reactors. It is rare for such a vast range of technological innovations to trace back so clearly to the work of a single researcher.

In recognition of his groundbreaking contributions, Lotfi received numerous national and international awards. He was elected to the US National Academy of Engineering and named a foreign member of the Finnish Academy of Sciences, Polish Academy of Sciences, Korean Academy of Science and Technology, Bulgarian Academy of Sciences, International Academy of Systems Studies, and Azerbaijan National Academy of Sciences. He was a fellow of the IEEE, the American Association for the Advancement of Science, the Association for Computing Machinery, the Association for the Advancement of Artificial Intelligence, and the International Fuzzy Systems Association.

Over the course of his career, he received an extraordinary number of honors for his contributions to engineering and science. Among them were the IEEE James H. Mulligan, Jr. Education Medal in 1973, awarded for “inspired and dedicated teaching, and distinguished leadership in system theory,” and the IEEE Richard W. Hamming Medal in 1992 for “seminal contributions to information science and systems, including the conceptualization of fuzzy sets.” He was also the recipient of the IEEE Millennium Medal in 2000 and the IEEE Medal of Honor in 1995, one of the organization’s most prestigious distinctions.

His accomplishments were recognized internationally as well. He received the American Society of Mechanical Engineers (ASME) Rufus Oldenburger Medal in 1993 and the Bernard Bolzano Honorary Medal for Merit in the Mathematical Sciences from the Czech Academy of Sciences in 1997. In 1992, he became the first recipient of the Kampe de Feriet Medal. Additional honors included the American Automatic Control Council’s Richard E. Bellman Control Heritage Award (1998), the Grigore Moisil Prize (1993), the Honda Prize (1989), the Okawa Prize (1996), and the AIM Information Science Award. In 1998, the Japan Society for Fuzzy Theory awarded him the SOFT Scientific Contribution Memorial Award.

In the fields of computing and AI, Lotfi earned the Association for Computing Machinery/Association for the Advancement of Artificial Intelligence (ACM/AAAI) Allen Newell Award in 2000 and the Norbert Wiener Award in 2003. In 1997, he received the J.P. Wohl Outstanding Career Award from the IEEE Systems, Man and Cybernetics Society. He was also honored as Civitate Honoris Causa by the Budapest Tech Polytechnical Institution in 2004 and received the V. Kaufmann Prize from the International Association for Fuzzy-Set Management and Economy that same year. Other accolades included the Nicolaus Copernicus Medal of the Polish Academy of Sciences (2005), the J. Keith Brimacombe IPMM Award (2005), the Egleston Medal (2007), and the Benjamin Franklin Medal of the Franklin Institute in Philadelphia (2009).

Additional honors included the Medal of the Foundation from the Trust of the Foundation for the Advancement of Soft Computing, the High State Award ‘Friendship Order’ from the President of the Republic of Azerbaijan, and the Transdisciplinary Award and Medal from the Society for Design and Process Sciences.

In total, he received 25 honorary doctorates. He was inducted into the Silicon Valley Engineering Hall of Fame (2006), the Heinz Nixdorf MuseumsForum Wall of Fame, and the AI Hall of Fame (2010). In 2013, he was awarded the BBVA Foundation Frontiers of Knowledge Award for the invention and development of fuzzy logic.