A Tribute to Prof. Dr. Da Ruan

253 Pages·2013·24.544 MB·English

by  Jie Lu, Etienne Kerre (auth.), Jie Lu, Etienne Kerre (eds.)

A Tribute to Prof. Dr. Da Ruan
Jie Lu and Etienne Kerre (Eds.)
A Tribute to Prof. Dr. Da Ruan
ABC
Editors
JieLu EtienneKerre
UniversityofTechnologySydney GhentUniversity
Australia Belgium
ISBN978-3-642-30306-7 e-ISBN978-3-642-30307-4
DOI10.1007/978-3-642-30307-4
SpringerHeidelbergNewYorkDordrechtLondon
LibraryofCongressControlNumber:2012938135
(cid:2)c Springer-VerlagBerlinHeidelberg2013
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This book is a present to Da who did not know he still had
so many sweet friends who thought well of and miss him.

This book is dedicated to Da’s family.

--Jie and Etienne
Foreword
Da Ruan's sudden passing away on July 31, 2011, at the age of 50, was a terrible
shock to all who knew him. At the age of 50, Da Ruan was at the peak of his
distinguished career. The author or co-author of over 270 papers and 36 books,
Da Ruan was a highly visible figure on the international scene as a researcher,
educator, an organizer of conferences, editor, lecturer, guest professor and, very
importantly, as a bridge between Asian countries, especially China, and the West.
But Da Ruan was much more than a prominent member of fuzzy logic and
computational intelligence communities. He was a man of vision, initiative, great
personal warmth and unbounded energy. His passing away is an irreparable loss—
a loss which will be keenly felt in coming years.
In 1985, Da Ruan was one of two students selected by the Chinese government
to study in Belgium toward a Ph.D. degree. He joined Professor Etienne Kerre's
group on fuzziness and uncertainty modeling, and received his Ph.D. degree in
l990. After receiving his Ph.D. degree, Da Ruan became a postdoc at the Center
for Nuclear Research in Mol. This was the beginning of his illustrious career and
his lifelong association with Etienne. This volume, “A Tribute to Professor Doctor
Da Ruan,” edited by Jie Lu and Etienne Kerre is a collection of eloquent tributes
to Da Ruan's life and work.
In most of my forewords, I spotlight a development in fuzzy logic and its
applications which I deem to be of importance. In the instance of this foreword, I
should like to comment briefly on what I consider to be an important trend—a
trend toward a fusion of probability theory and fuzzy logic. Underlying this trend
is the realization that, in large measure, uncertainty involves a mixture of
fuzziness and probability. In this mixture, probabilities and events are commonly
described in a natural language. I have long advocated the view that standard
probability theory cannot deal with problems in which probabilities and events are
described in a natural language. To deal with such problems, probability theory
must be generalized through addition of concepts and techniques drawn from
fuzzy logic and, more particularly, the formalism of Computing With Words
(CWW).
An important concept which is the child of the marriage between probability
theory and fuzzy logic is what I call a Z-number. I introduced this concept in my
lecture at the World Conference on Soft Computing in San Francisco, in May
2011. After my lecture, I was approached by Da Ruan. His feeling was that the
concept of a Z-number has the potential for many practical applications, and that
he intended to explore what he felt was a new direction. It is a source of deep
regret for me that his intention did not materialize.
VIII Foreword

Briefly, a Z-number is an ordered pair of fuzzy numbers, (A, B), in which A is
a fuzzy value of a variable, X, and B is the fuzzy probability that X is A.
Typically, A and B are described in a natural language. As a simple illustration,
(usually, small) is a Z-number. An interesting question is: What is the square root
of (usually, small)? Problems of this kind fall within the province of computation
with Z-numbers.
The importance of the concept of a Z-number derives from the fact that in
many realistic settings our knowledge of the value of a variable is uncertain.
Computation with Z-numbers opens the door to construction of models in which
the values of variables are certainty-qualified, e.g., usually, very likely, surely, etc.
Clearly, in most realistic settings such models would be a better approximation to
reality than models in which the values of variables are not qualified. An
intriguing application of the concept of a Z-number is an if-then rule in which the
consequent is usuality-qualified. A simple example is: If unemployment increases
then usually stock market declines.
What would Da Ruan do with the concept of a Z-number? It is a question that
can be raised but not answered. It is a painful realization that Da Ruan is not with
us. He was a truly unique individual.
Lotfi A. Zadeh
Berkeley, California, USA

Prof. Da Ruan and Prof. Lotfi A. Zadeh in FLINS2008, Madrid
Preface
On 1 August, 2011, very sad news reached our scientific research community, we
didn’t believe it and we don’t want to believe it, but it is true: ‘Our dear friend,
Prof. Da Ruan, suddenly passed away yesterday’.
Only 50 years old, Da Ruan was in the prime of life, as a scientist, in the prime
of career; no chance to prepare, and no time to say good-bye, suddenly left us for
his heavenly abode, far away from his family and friends.
Our hearts were broken, we were full of sorrow, and tears streamed down our
faces. How desperately we hoped that it was not true! The whole fuzzy logic
research community was shocked and saddened by the loss of Da Ruan. At first,
people questioned if it was indeed true. It seemed impossible – the loss of such a
great man was truly shocking and caused heartfelt pain throughout the community.
“Providence is always hard to ask for”—an incurable pain for us, for our hearts.
People found various ways to channel their grief for their close friend.
Hundreds of emails quickly spread the tragic news throughout the world, in
memory of Da. The large number of emails was testimonial to the high respect in
which he was held, and how widely he was liked, both personally and
professionally.
Some emails recalled fortunate meetings with Da and how he impressed people
with his sunny smile and friendly personality. Others talked of their long-time
research collaboration with Da. Some expressed appreciation to Da for helping to
build their careers and achieve their goals. Some reflected on their first visit to Da
at SCK•CEN and how he took care of them. There were expressions of
appreciation for assistance with difficulties, and panegyrics about Da's brilliant
speeches. All emails were full of accolades, admiration, high praise and honour
for Da Ruan.
Indeed, this huge outpouring of grief, along with the email accolades and
expressions of admiration, high praise and honour for this man, was the
motivation and driving force behind this book. Producing and editing this book –
to the memory of Da, dedicated to his family, for his colleagues, friends and
students – has been a great honour and we hope that it will inspire future
generations in the fuzzy logic community. We hope that it reflects Da's noble-
minded and distinguished values and that it will have long-term significance in the
research community.
Da Ruan was born in Shanghai where he spent a happy youth in the
international metropolis. Full of vigour and dynamism, he completed his studies at
Changzhi High School in 1979 with distinctive results, which earned him
X Preface

admission to Fudan University, a top Chinese university. After four years, he
graduated with Honours and became an Associate Lecturer in the Department of
Mathematics at Fudan University. In 1986, he was selected as an 'excellent youth
scholar' to study at Ghent University, and in 1990, his PhD degree was conferred
there. Since 1991, Da worked at SCK•CEN, starting as a post-doctoral researcher
and progressing to a leading scientist position.
Da Ruan's short life was colourful and creative. He was a motivated and very
productive scientist, publishing 36 books and 270 papers in journals and
conferences. He led several very important fuzzy logic research projects in nuclear
science, decision systems and risk analysis. His extraordinary contribution made
him an undisputed leader and figure of authority in his fields of research.
He was a quick thinker and surpassed many others with his energy and
indefatigability. He was an excellent leader. In 1994, at only 34 years, he took the
initiative to establish the FLINS (Fuzzy Logic and Intelligent technologies in
Nuclear Science) conference series, which grew to become the world's leading
conference in the fuzzy information processing field. He continued to play a
leading role, establishing the ISKE (Intelligent Systems and Knowledge
Engineering) international conference series in 2006 – this has become a very
popular conference in the area of intelligent systems. He also founded the
International Journal of Computational Intelligence Systems (IJCIS), which, in
the few years since its introduction, has acquired a very good reputation and
international standing. He made outstanding contributions in the research fields of
fuzzy logic, fuzzy decision making, computational intelligence, risk management
and, in particular, the application of these advanced techniques in real-world
nuclear science and nuclear industry. He was a very influential man throughout
the world.
Da was very committed to his work and career, and was adept at handling
complicated and challenging issues. He was confident, honest and open, his work
was thorough, and pressure always excited him. His success can be attributed to a
combination of his brilliance, expert knowledge of his scientific research, and his
willingness to work hard and always push himself just that little bit further. He
was therefore great fun to work with and people loved to contribute to the books
he edited and attend the conferences he organised. As the undisputed leader of his
community, Da's absence at the recent ISKE2011 conference held in Shanghai
was consequently intensely felt.
Da was a charming and personable man with a cheerful and friendly
personality and scholarly bearing. He had a playful sense of humour and liked to
tell jokes and funny stories. He enjoyed fine food, particularly seafood, and he
delighted in cooking delicious Chinese meals.
He loved his hometown, Shanghai, and his mother country, China. Over the
last 20 years, he was a Visiting Professor at many universities in China and he
Preface XI

supervised, trained and helped many Chinese scholars to become world-class
researchers. He promoted effective communication between Chinese and Western
cultures in our research community, benefiting both Chinese and Western
scholars.
Da was a warm-hearted person who cared deeply about people and those he
met all wanted to be his friend. He had an extensive community of friends and
colleagues, and was very well-connected. People sought Da out for collaboration,
so that he had over 100 published papers with researchers from other countries
such as Australia, China, France, Italy, Spain, Turkey, UK and the US, all of
whom are all proud of their collaborative experience with Da.
The authors of this book are all Da’s friends; 88 academics from 47 institutes in
17 countries. They are respected senior, and junior, scholars; they are also Da’s
colleagues, classmates and peers; they are world-class researchers, and distinctive
academics. The “father of fuzzy theory”, Professor Lotfi Zadeh, 90 years old, has
written the foreword of this book. Professor Yager, the Editor-in-Chief of the
international journal Intelligent Systems, Professor Wang, ex-Editor-in-Chief and
Professor Pedrycz, current Editor-in-Chief of the international journal Information
Sciences, Professor Kacprzyk, Editor-in-Chief of Studies in Computational
Intelligence by Springer, and Professor Zimmermann, the founder of the
international journal Fuzzy Sets and Systems, all write of their particular
experience with Da.
The majority of these authors knew Da well, becoming his friend through
FLINS conferences. Although their expertise is in programming and mathematics,
they have written touching stories of their experience with Da, expressing their
grief at losing their dear friend. Reading these stories, we were deeply touched –
and surprised – to find out that our scientists have become great writers.
Editing this book has not been easy. Emotions were constantly stirred
throughout the process. Photos of Da are constant reminders of his loss; stories
about him, his life, his work, re-awaken the grief. We have encouraged and
supported each other throughout the editing process, and the book is a sincere
tribute by all authors to Da Ruan.
Da's friends and colleagues have contributed over 60 chapters and more than 70
pictures, and we have been deeply moved by the articles. This has also been a gift
to us, enabling us to better understand Da's contributions to the research
community and come to know more about his life and his work. We more clearly
appreciate his humanity and love of life, and his zeal, commitment and ambition
in his academic life. Most importantly, editing this book about Da has taught us
that, although knowledge and talent are important, it is sincerity, honesty and
kindness that are the true indicators of the greatness of a person.
We wish to thank our all wonderful authors and the cover page designer,
Mr. Chen. Our grateful thanks go to Tom and other Springer staff for their support
in publishing this book.
XII Preface

Da has gone, but we are lucky to have been his friend. We are lucky to have
worked with him. It is up to us to continue his work by providing a friendly,
compassionate community and fun environment within a vibrant, exciting and
motivated research community – to live up to Da's memory.
Da will remain in our hearts forever.

15 March 2012 Jie Lu
University of Technology Sydney
Australia
Etienne Kerre
Ghent University
Belgium