In Memory of


Lotfi A. Zadeh

1921 - 2017

We are all saddened by this loss. Lotfi Zadeh had many great ideas, he started many interesting research directions. The best way to remember him is to continue working on implementing his ideas. Any new application, any new improvement of fuzzy technique will be a reminder of Lotfi Zadeh's legacy.

Vladik Kreinovich
University of Texas at El Paso

We lost one of the greatest thinkers of the last decades. A scientist with unusually clear vision and an abundance of new ideas - one of the most cited researchers ever. He is known as the Founder and Father of Fuzzy Sets, but before that he already produced remarkable results in System Science (I posses a copy of his edited book, that he later signed and dedicated to me) - and he came out with so many new ideas about Soft Computing as a general discipline, Precisiated Natural Language, and many others... He founded a community, the BISC group that is still keeping together thousands of scientists all over the world, an excellent place for a newcomer to the field to obtain valid answers to his or her questions about any area of SC, He was an extremely modest and friendly person, in his behavior, his clothing, his eating. He never told any bad word to anybody, even to those who tried to diminish the importance of his ideas - his answer was only: I take it as a compliment. I was so lucky to have him as a fatherly friend, who already sent me his works in the early 1970-s, and we met in person in 1975, the first time. He always encouraged me to continue research, mentioned it in his plenary talks when he found connections to his chain of thoughts. I feel lucky to have had so many personal meetings with him, and I keep the memory of the last dinner in his favorite Chinese restaurant (not the one he used to go to after the seminars...) Dear Lotfi, rest in peace! Goodbye forever!

Laszlo T. Koczy
Budapest University of Technology and Szechenyi Istvan University (Gyor), Hungary

I am so sad to hear this news. I am so thankful for him to introduce the new research line about Fuzzy sets and Z numbers. Peace in rest prof. Lotfi Zadeh.

Tofigh Allahviranloo

Lofti Zadeh is gone after devoting his life to this community he created from an idea that now iluminates every field of knowledge. A great scientist and one of the greatest personalities I ever met. He was able to attract a second generation of wonderful pioners that became his friends. His kindness is the first thing that came to my mind when I received the bad news. Always trying to help, always offering new ideas to everybody, always putting people to work together. I am personally grateful for the support of Lotfi and Fay to my wife, because they took care of her when I had to leave Berkeley during several months. Lotfi's heritage is his love to Science, Humanity and Friendship. We should never forget what he has been teaching us. Now we have to stand together, all fuzzy associations and all their members, to continue developing his vision.

Javier Montero
IFSA Council & Complutense University of Madrid, Spain

SIGEF expresses its sadness by the death of Lofti Zadeh. Our association was born to contribute to enrich his contribution in the field of Fuzzy sets and we had the honor that he supported the publication of Fuzzy Economic Review as honorary director. His visit to Reus, headquarters of SIGEF, is a memory that we will never forget. He allowed us to know the great scientist and man who was Lofti Zadeh.

Antonio Terceño Gómez
International Association for Fuzzy-Sets Management and Economy (SIGEF)

May the father of fuzzy logic rest in peace!

Gaurav Nakum
IIT Guwahati

I was shocked by this sad news. Zadeh is a great man. He is very kindhearted for the new scholars. I have some communication with him by email. I though he would not reply me but in fact he replied me in just one day. I was touched by his patience and kind helps. May he be good in the heaven. God bless him.

Huchang Liao
Sichuan University, China

We started out knowing eachither in a student-professor-relationship. I admired your innovative ideas and how you stood up against those, who (at the time) thought that Fuzzy Logic was a silly hobby of you and not worth going into. In later years, we became acquainted as colleagues and I always enjoyed exchanging thought with you, esp. in the field of NLP that I have started plunging into at UC Berkeley, but alsolater in industry and now again in university. Your ideas and mindset will stay alive in my lectures and in my heart. Thanks Lotfi! Bettina

Bettina Harriehausen
Univ. of Applied Sciences, Darmstadt, Germany

Lotfi brought me from Paris to UCB in the winter of 1975 to join his research team of fuzzy information processing. I have known a great man. Hung T. Nguyen

Hung T. Nguyen

I met Lotfi at a conference. He had a knack for finding the women, & there were exactly two of us--one all lovely & sweet, pretty as a model & dressed like an absolute confection straight out of a 1960s ladies' magazine, & little me, dressed like an engineer. I don't think he went anywhere after that without one of us on each arm, which made it a little challenging for him to hold his drink. But somehow he managed. When I told him about my control theory dissertation using fuzzy logic, Lotfi took it upon himself to advise me by phone every few weeks. I had already defended, but the committee had deadlocked. After months of watching the back-and-forth in bemusement, Lotfi read my dissertation. Finding nothing wrong, he offered to e-mail my committee. When I named the point of contact, Lotfi said, "Oh, yes--I remember him. I met him once 10 years ago at a conference." Lotfi was 87 at that point--what a memory! He literally shamed my doctoral committee into passing me. For that, I'll always be grateful. Lotfi gave a talk at NIH ~5 yrs after that. He looked so frail! And then...he began to speak. His face lit up, his back straightened, his voice projected...he became ten feet tall. He filled the room with his passion, his presence, & his light. Lotfi was a student of the universe. He strove to understand everything & create justice wherever he found injustice. He was a towering intellect. I am honored & humbled to have had the privilege of walking the earth with him.

Amy J. O'Brien, D.Sc.
IEEE Senior Member

Lotfi Zadeh was not only a great scientist, with many intuitive ideas, he was also a great leader. * his always positive attitude, starting with his "Take everything as a compliment" attitude to criticisms, * his helpful nourishment and promotion of new researchers, * his eagerness to combine his ideas with competitive computational intelligence ideas, be it probabilistic techniques, neural networks, genetic algorithms, into even more successful combinations, * his ability to explain his ideas both to the technical audience and to the general public -- all this made him a great leader, as well as the fact that * he was truly passionate about science, about success of his students and colleagues, I think about everything in life. We need more people like him.

Olga Kosheleva
University of Texas at El Paso

In 1994, I went to Berkeley to meet Lotfi Zadeh and interview him for our magazine Azerbaijan International because of his early ties in Baku. He had lived there for the first 10 years of his life before Stalin ousted foreigners and his family moved to Tehran. Despite the fact that I was not a mathematician or computer specialist, he was very gracious with his time. Naturally, the articles that resulted concentrated more on human characteristics and perspectives. Our friendship continued over all these years. From time to time, when I went to Baku, I would send him photos of the apartment that he used to live in a child and the elementary school that he had attended. It turns out that he was immensely well-read from early childhood and deeply impressed with the idea tha each person must find a way to contribute to society. Looking back, some of the qualities that stand out for me - are his humility. It reminds me of a proverb from that part of the world: “The tree laden with fruit, hangs low.” Articles that Lotfi and I worked on together: Famous People Then and Now Lotfi Zadeh: Short Biographical sketch What is Fuzzy Logic?

Betty Blair
Azerbaijan International magazine

I didn't have the chance of meeting him personally, but I will always be grateful to Prof. Zadeh. His original idea about fuzzy sets, and his later works that hinted at a "computing with words" paradigm have been an inspiration for me. Although my theoretical background in fuzzy sets is not as extensive as I would like it to be, I'm quite convinced of the usefulness of approaching the application of fuzzy sets through empirical means, in order to model the meaning of imprecise linguistic concepts that can be grounded on data. I hope that my research in this regard can be useful for building better natural language generation (NLG) systems and establishing fuzzy sets as another useful tool that can be seriously considered within the NLG discipline. Thank you, Prof. Zadeh.

Alejandro Ramos
Universidade de Santiago de Compostela, University of Aberdeen

I met Lotfi Zadeh several times. The first one was in Paris, at UPMC, in a small classroom. He was explaining the concept of Computing with words and it was fascinating to me. Later I saw him several times at many conferences and I especially remember the time when he was explaining the generalized theory of uncertainty: I was all aware of how lucky I was to have the opportunity to listen to him and to talk to him. Professor Zadeh, we will miss you so much.

Isis Truck
University Paris 8, France

Prof. Zadeh is the great AI scientist of the world.He is not only the father of the fuzzy logic, fuzzy mathematics, but also the kind grandfather of my life. I miss him so much! I wish Professor Lotfi A. Zadeh have a good time in heaven.God bless him!

Liu Yi
Handzhou Dianzi University

A pleasure meerting you in several conferences and meetings. We will continue working on implementing your ideas on fuzzy logics and fuzzy systems applications.

Núria Agell
ESADE, Ramon Llull University

I first met Lotfi Zadeh when I was a young researcher and I was organizing an event in 2001, just after the 9/11. I invited him to give a talk and, despite the difficulties he travelled too many hours to be present. That's how he was, always generous. I will always remember him as someone who inspired so many of us and made us think differently about so many things. Thank you.

Pedro Melo-Pinto

The 20th century was one of true giants in scientific endeavors ranging from relativity (Einstein) to quantum mechanics (Planck, et. al.) to theories of random noise (Rice) and communications (Shannon). Into this fertile field was born the science of artificial intelligence, whose greatest advances arguably derived from the seminal work of Lotfi Zadeh in fuzzy sets and systems. I first met Lotfi as a graduate student at UC San Diego in the early '70s, and was immediately taken by his novel perspectives on human reasoning and his extraordinarily approachable manner with all who were interested in his work. Even during a large, frenetic conference, at which he was often a keynote speaker, Lotfi would take the time to discuss one's research interests, and would never allow you to buy lunch for him! One of the most profound statements that I ever heard him make was, "If T is a theory, then T can be fuzzified." Lotfi gave us the tools needed to make this statement feasible. We will miss him dearly, but his legacy is secure. Requiescat In Pace, dear Lotfi.

Terry Rickard
Till Capital Ltd., Meraglim, Inc.

Dear Prof. Zadeh, Our forever mentor and friend, As a lecturer and researcher of fuzzy optimisation, I am on behalf of the member of the Lab of Fuzzy Optimization and Soft Computing at the Department of Industrial Engineering and Engineering Management, National Tsing Hua University, Taiwan, ROC to pay our deep mourning and condolences. Although we have met only few times, for more than 20 years, we have followed what you have guided to clarify fuzziness in different aspects. You have not only inspired us to view uncertainty from different angles, but also opened many research doors towards such a unstable and chaotic world. Your spirit of love to this world also has broken down the wall of the people from all over the world, from your photos, your non-stop attendance of different conferences and gathering. Your appearance always encouraged our for-going footsteps. For this, we thank you from our deepest heart. While your body has rest in peace, your spirit will always remain in our heart. Yours sincerely, Hsiao-Fan Wang Tsing Hua Chair Professor Emeritus, Head of Fuzzy Optimization and Soft Computing Lab., Department of IEEM, National Tsing Hua University, Hsinchu, Taiwan, ROC email:

Hsiao-Fan Wang
IEEM, National Tsing Hua University, HsinChu, Taiwan, ROC

It is with great sorrow that we have heard the sad news that Professor Lotfi A. Zadeh has passed away. He kindly encouraged us by showing novel paradigms and new directions related to fuzzy logic and soft computing. His passing is the greatest loss to us and our society. On behalf of Japan Society for Fuzzy Theory and Intelligent Informatics (SOFT), we tender deepest sympathy and sincere condolences to you and the whole family. Yours sincerely, Isao Hayashi (President of SOFT) Makoto Fujiyoshi (Vice-President of SOFT) Masahiro Inuiguchi (Vice-President of SOFT)

Isao Hayashi
President of SOFT, Kansai University

I fondly remember having coffee in his favourite Berkeley coffee shop, his deep engagement with our conversation which took us back to his office that had narrow corridors of piled up books and my unintended knocking down a column! We had a good laugh while building the column back. Such a big loss to the scientific world. My deepest condolences to his loved ones.

Taner Bilgiç
Bogazici University, Istanbul

Il prof. Zadeh è universalmente considerato il padre della logica fuzzy e, fino agli ultimi istanti della sua lunga vita ha contribuito attivamente alla discussione sui principi della granularità e gradualità dell'informazione alla base della sua logica. Egli aveva una visione lungimirante e controcorrente della Scienza che ha ispirato migliaia di ricercatori, oltre a una rara gentilezza e disponibilità al dialogo. Riposi in pace.

Corrado Mencar
Università degli Studi di Bari "Aldo Moro"

I am so sad to hear this bad news. I am so thankful for him to introduce the new research line about Z numbers in 2012. Peace in rest prof. Lotfi Zadeh.

Yabin Shao
Chongqing University of Posts and Telecommunications

The legacy of Prof. Zadeh is immense. I was a graduate student back from 1979 to 1980 at UC Berkeley and Prof. Zadeh was my Master Thesis advisor. We kept in touch and saw him, and Fay, almost every year since then. The last, and most pleasant, time was in Madrid in 2013 on the occasion of the "BBVA Foundation Frontiers of Knowledge Award" in the ICT field, one of the major awards he received (that is endowed with half a million US$ for the winner). I was, and I still am, the secretary of the ICT Jury and I felt very proud of the jury's decision that year! because he was not only an immense scientist but he had also always been very proud and very supportive of the Spanish Fuzzy community. The BBVA Foundation asked me to write an obituary, which I did, that has been published in a major Spanish newspaper (those that can read Spanish can read it here: I ended the obituary by saying that Prof. Zadeh is one of those colossal scientists that Newton referred to with his famous sentence: "If I have seen further than others it is by standing upon the shoulders of giants".

Ramon Lopez de Mantaras
Artificial Intelligence Research Institute

Professor Zadeh will be missed. May the father of approximate reasoning and fuzzy logic rest in peace!

Bilal M. Ayyub
University of Maryland, College Park

I met Prof. Zadeh in some conferences and I always appreciated the height of his mind and modesty and kindness of his appearance. Thanks Prof. Zadeh. It was a great honor to meet you

Piero Mella
University of Pavia, Italy

Мир потерял и одновременно приобрел великого учёного и в тоже время весьма простого и скромного человека. Лютфизаде наша гордость... Азербайджан испокон веков славится своими одаренными и талантливыми личностями. Будем надеяться, что в ближайщем будущем последователи великого ученого обрадуют его светлую память и мировое научное сообщество значительным прогрессом и достижениями в теории нечеткой логики. Аллах ряхмят елясин!

Nigar Akram Abdullayeva
Azerbaijan State Economic University

Professor Lotfi Zadeh was a man whose contributions to the field of Intelligent systems are noteworthy. This longtime UC - Berkeley researcher was a pioneer in the truest sense of the word. In recognition of his influential works, Professor Zadeh received many awards and honors, yet, when the world lost him, we lost much more than a scientific giant. His associates lost a wonderful mentor, a good friend and his family lost a loving father and grandfather. We had the opportunity to work on a couple of editorials and also co-organized a scientific event in 2005. I, too, will miss Lotfi greatly. Professor Zadeh's amazing success stemmed from his exceptional ability to recognize scientific opportunity when it came along, and his extraordinary persistence in pursuing that vision. Professor Zadeh, the world has been greatly blessed by your remarkable contributions. We will miss you. RIP! Ajith Abraham

Ajith Abraham
Machine Intelligence Research Labs (MIR Labs)

It is a big loss in the field because we lost a renaissance man and a great researcher who is well-known as the Founder of Fuzzy Sets and Soft Computing. Zadeh's brilliant ideas truely impact on the fields of Mathematics, Computer Science, Engineering, and other related fields. Professor Lotfi Zadeh will always live in our hearts.

Miin-Shen Yang
Chung Yuan Christian University, Taiwan

Lotfi Zadeh was a great scientist and a great man. He taught us that curiosity is central in the pursuit of knowledge and the enjoyment of life. His humor was part of the seriousness with which he dealt with everything. Above all he was a warm human being. We are thankful for his lessons.

Yannis A Phillis
Technical University of Crete

Humanity should be thankful to this great man. He makes the life more comfortable and luxurious for the common man. Because of his idea, scientists made the new camera and new machines which are based on fuzzy logic. He is the man bigger than one life, he made the life of many researchers and scientist who completed their PhDs and research work on his idea. He inspired many lives. I have seen many people who criticize his theory of fuzzy logic, but after some years they also started work on this theory. Lotfi Zadeh is the name of motivation for the researchers and scientists. Zadeh was the gift of GOD for the humanity.

Tabasam Rashid
University of Management and Technology, Lahore, Pakistan

Мир потерял и одновременно приобрел великого учёного и в тоже время весьма простого и скромного человека. Лютфизаде наша гордость... Азербайджан испокон веков славится своими одаренными и талантливыми личностями. Будем надеяться, что в ближайщем будущем достойные последователи великого ученого обрадуют его светлую память и мировое научное сообщество значительным прогрессом и достижениями в теории нечеткой логики. Аллах ряхмят елясин!

Nigar Akram Abdullayeva
Azerbaijan State Economic University

I had a chance to meet him at University of Toronto where he gave a speech about Fuzzy Logic. At that time I was about the finish my dissertation. We, Dr. Turksen, students in Fuzzy lab. And I, had a lunch full of exchanging ideas. Still I am repeating his words to let my students know little about Fuzzy Logic. Rest in peace professor. We won't forget you!!!

I. Ozkan
Hacettepe Univ.

I first met Lotfi, when I was a starting PhD student, at the 1992 World Automation Congress in Santa Fe, New Mexico. He later hosted me in 2006 and most recently in 2017 on both of my sabbaticals at UC Berkeley. He and Fay were both so gracious and kind. Prof. Lotfi Zadeh was a true visionary, respected academician, and great inspiration. It always amazed me how he could simply introduce a profoundly new concept, only to be followed by so many at various conferences and seminars. Fuzzy logic, Soft Computing, Z-Numbers, Machine Intelligence Quotient are only few outcomes of this incredible man’s intellect. Many debated his nationality, whether Azerbaijani, Iranian, Russian or American. The truth is, he belonged to the world. His timeless contributions will continue to resonate within the scientific world and to profoundly impact human lives everywhere. Lotfi, we will miss you here at the roundtables. May God bless you.

Mohammad Akbarzadeh
Ferdowsi University of Mashhad

LOTFI A. ZADEH IN MEMORIAM EURO WG on Fuzzy Sets marked the start in 1974 of European research on fuzzy sets. Lotfi inspired, motivated and encouraged this activity but – as was always his way – never tried to manage or dominate the work we carried out. The early focus was on Systems Research (at EMCSR in Vienna) and Operational Research (at the EURO Conferences) which gave some early breakthrough results. Even more important were the networks that European researchers formed. This continued - on a much larger scale – when IFSA was formed in Brussels in 1985 and gradually became a global move-ment. Lotfi was always there at our meetings, even at an advanced age, giving thought-provoking keynotes, encouraging young researchers and making sure that people who should work together met and got to know each other. His impact and importance is without comparison. We who had the privilege of knowing Lotfi from the early days of fuzzy sets and benefited from his encouragement and support feel a deep debt of gratitude – we would have accomplished much less, if Lotfi had not been there. May he rest in peace, his legacy will continue for generations.

Christer Carlsson
Institute for Advanced Management Systems Research, Finland

We have lost a great human being and a brilliant scientist that will never be replaced and whose legacy will never be forgotten, may his soul rest in pace.

Sergio Gerardo de los Cobos Silva
Universidad Autónoma Metropolitana

Lotfi A. Zadeh inspired a whole generation of scientists. His death fills us with sorrow. We will never forget him. May God give him eternal rest.

Miguel Ángel Gutiérrez Andrade
Universidad Autónoma Metropolitana

I had the chance to meet him personally and many more chances to make communications with him. This was the greatest advantage to me. Here in EU, we prepared for publication a Springer book illustrating the development of his ideas in both traditional and informal scientific applications. His great name and ideas will never die.

Vladimir Jotsov
ULSIT-Sofia, Bulgaria

The world has lost one of its greatest THINKERS. Professor Lotfi A. Zadeh has been instrumental in my intellectual development to examine the contribution of Intuitionist approach to mathematics and logic. He thus provided us with the way to understand the debate between Russell and Brouwer in dealing vagueness and incompleteness in information representation and paradigms of thought. My works on information, knowledge and principles of opposite with relational continuum and unity have benefited substantially from the great contributions ant teachings by the GREAT THINKER LOTFI ZADEH. Our responsibility is to continue his great contribution in directions that are peacefully beneficial to general existence. MAY HE REST IN PEACE WITH LOVE AND BLESSING.