In Memory of Professor Ming-Chit Liu
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♦ Obituary (by Professor Y.K. Lau and Professor Patrick T.W. Ng) ♦ A note on Prof. M. C. Liu (by Professor M.K. Siu) ♦ Tributes ♦ Photo Album |
Professor Ming-Chit Liu (1937-2023)
Our former Chair Professor Ming-Chit LIU (廖明哲) passed away in Los Angeles on 24th March 2023 at the age of 85. He is survived by his wife Ms. Moon-Chi CHEUNG and two sons Kay-Wai LIU and Yun-Wai LIU.
Professor Liu was born on 30th December, 1937 in Macao. He did his B.Sc. degree in Chung Chi College, The Chinese University of Hong Kong (CUHK) from 1961 to 1965. He then received his B.Sc. Special from The University of Hong Kong in 1966. Professor Liu devoted more than thirty years of his life in The University of Hong Kong (HKU). He joined the Department of Mathematics of HKU in 1966, working as a demonstrator and at the same time pursuing the study of Master of Science under the supervision of Professor Yung-Ming CHEN.
The work of his master thesis was published in two papers in Journal of the London Mathematical Society and Proceedings of the American Mathematical Society respectively. The paper in the former journal partially solved a problem of the famous mathematician John Edensor Littlewood (Cambridge) and the other paper is concerned with a problem of Paul Erdős in number theory. In fact, Littlewood was the external examiner of Professor Liu’s master thesis and in his report, one can find
“This is a perfectly clear case. In fact if the thesis were for the Cambridge Ph.D. it would in my opinion have obtained the degree.”
After receiving the M.Sc. degree in 1969, Professor Liu continued the study of Doctor of Philosophy in HKU and meanwhile he was promoted to Assistant Lecturer in 1971. His doctoral thesis ``Some asymptotic approximation theorems in real and complex analysis" was completed in 1973, the work in which was published in six papers in international journals such as Mathematische Zeitschrift, Canadian Journal of Mathematics, Quarterly Journal of Mathematics, etc.
Following with the completion of doctoral degree, Professor Liu was promoted to Lecturer in 1973 and continued his career in HKU. He was directly promoted to Reader in 1983, bypassing the rank of Senior Lecturer, and then to Professor in 1990. During these three decades, Professor Liu switched his research focus from complex analysis to analytic number theory, particularly on Diophantine equations and Diophantine inequalities involving prime numbers. Two main open problems in this area are the so-called Binary Goldbach Conjecture (posed in 1742) which says that even integer greater than 2 is a sum of two prime numbers and the weaker form, known as Ternary Goldbach Conjecture (also posed in 1742), which states that every odd integer greater than 7 is a sum of three odd primes. For the Binary Goldbach Conjecture, Jingrun CHEN (1966, 1973, 1978) showed that all sufficiently large even numbers are the sum of a prime and a product of at most two primes. It was through the effort of our Department and Professor Liu that this important work of Chen became accessible to the West after the Cultural Revolution. For the Ternary Goldbach Conjecture, Professor Liu and Tianze WANG had shown in 2002 that every odd integer larger than exp(3100) is indeed a sum of three primes. This result greatly improves the threshold exp(exp(11.503)) obtained by Jingrun Chen and Tianze Wang in 1989. In 2014, Harald Helfgott published a preprint containing a proof for Ternary Goldbach Conjecture. Helfgott’s proof is widely accepted in the mathematics community, but as of 2023 it has not yet been published in a peer-reviewed journal. Professor Liu published over sixty research papers and more than three-quarter of them are in the field of number theory. Professor Liu has founded and developed number theory to be a main research area in HKU. He supervised a dozen of graduate students and all of them completed theses of topics in number theory.
Professor Liu has many important contributions in academic connection and activities around. For instance, in 1990s, he helped organize international conferences on number theory in HKU and facilitated the invitation to the three Fields Medallists Alan Baker, Enrico Bombieri and Atle Selberg to visit HKU. Through the efforts of Professor Liu, our Department has long and strong connection with the school of Analytic Number Theory in China founded by the late Professor Loo-Keng HUA (with Szu-Hoa MIN). For example, in addition to Professor Hua’s visit in 1980, Professor Liu has invited distinguished analytic number theorists like Yuan WANG and Chengdong PAN to visit HKU in the 1990s. He also nurtured young scholars, in particular, the present Vice Principal of Shandong University, Jianya LIU, the Vice President of North China University of Water Resources and Electric Power, Tianze Wang, and the Director of UNESCO Institute for Information Technologies in Education, Tao ZHAN, had visited HKU and worked collaboratively with Professor Liu in the late 90s.
Professor Liu has been teaching first year calculus for many years. His lectures were always clear and well-organized and it was very fortunately for many students to learn how to read and write epsilon-delta proofs from him. Professor Liu also taught a number theory course and a postgraduate complex analysis course. These courses provided rigorous training to analytic number theory. Besides serving for various departmental and university committees in HKU, Professor Liu also involved in various review and selection committees for several local universities and the Hong Kong Government. For example, he was a member of the Scientific Committee of the then newly founded Institute of Mathematical Sciences of his alma mater CUHK in 1996. Professor Liu also served as a Vice-President of the Hong Kong Mathematical Society from 1996 to 1998.
Professor Liu retired from HKU in 2000, and the Department of Mathematics established in 2005 the Liu Ming-Chit prize in mathematics with his generous donation. Now the Department maintains a team of five people working on number theory or closely related areas.
Professor Liu will be very much missed by all of us. The remembrance of his kindness and his most rigorous scholarship will always stay with us. May he rest in peace.
Yuk Kam LAU and Patrick, Tuen Wai NG
Professors
Department of Mathematics, HKU
30th March 2023
A note on Prof. M. C. Liu
It saddens me to know that a dear old colleague departed from us. Everyone who has the good fortune to have been a colleague or a student of Professor M. C. Liu will miss him, such a modest, dedicated, rigorous mathematician and a gentle, kind, friendly man.
When I was in my third year in HKU, Ming Chit was studying for his B. Sc (Special) degree. He stayed on as a demonstrator and a master, subsequently a doctoral, candidate who studied under the supervision of Professor Chen Yung Ming, a jovial and likable member in the department affectionately known by the name of “Chubby Chen [肥陳]”. Professor Y. M. Chen was also a dedicated mathematician, perhaps even more dedicated than Ming Chit, and he remained single throughout his life, devoting all his time doing mathematics and taking care of his mother. A well-known story about Ming Chit that went the rounds in the department is what happened on his honeymoon trip soon after he became a graduate student of Professor Chen, who apparently did not quite realize what honeymoon meant for a newly wedded couple. For him, it was simply natural and logical that he should tell Ming Chit to bring along some papers and try to settle the Littlewood Conjecture on the trip. He was thinking that Ming Chit did not have any teaching duty on the honeymoon trip and should have plenty of time to think about the problem!
There was no example class nor tutorial during the B. Sc (Special) year, so I did not meet Ming Chit in my fourth year at HKU, but only knew him by name then. It was when I returned to teach at HKU in 1975 that we became colleagues and good friends. For a couple of years, we lived in the same building of Cambridge Garden on Babington Path, until he moved into the university quarter in Sandy Bay. In the summer of 2000, six months after I first took up the headship of the department, Ming Chit retired and left the department, went to Los Angeles with Mrs Liu and settled down there with their sons and grandchildren in that summer. In the ensuing years I met Ming Chit and Mrs Liu rather frequently each time they came back to Hong Kong for a visit, because they would stay at Robert Black College and were around the campus. They did not come back since five or six years ago. Last year Ming Chit sent us a nice drawing of a sailboat he performed. I did not know his health was deteriorating then, but thought that he developed a new interest and talent in drawing. Besides, I thought that he was trying to convey a message of blessing.
Although Ming Chit might look like a serious and quiet person who seemed to be immersed only in conversations related to matters mathematical, he had a strong sense of humour as well, and usually would poke fun at the right spot.
May our dear friend and colleague Ming Chit rest in peace.
SIU Man Keung
April 2, 2023
Tributes
Professor Liu was the instructor of the part on analysis in the course Math B I took in my first year at HKU. His lectures were extremely organized, and as far as I can remember, at the end of each lecture there was always a pinnacle which made me feel that I had just experienced something important (of course, whether I understood anything was another story....). I have been trying to replicate this trait of Dr Liu's since I started teaching some twenty years ago, but needless to say, I still have a long way to go.
CHAN Wai Kiu, Wesleyan University (HKU, B.Sc. 1988, M. Phil. 1992)
April 6, 2023
遽聞廖明哲老師辭世，不勝懷念。本人1975∼1977年（當時二年級及三年級）就教於廖明哲老師，他的教學十分認真，教我們Analysis-II和Complex analysis。通常每一課他會先綜合上一課的內容（當然第一課除外），令我們容易掌握接下來的講授。然而，他本身的數學研究水平相當高，「強將手下無弱兵」，他是陳永明教授的首徒。據說他隨陳教授修讀後不久結婚，陳老師說，你反正渡蜜月，沒甚麼事情（不用教學），於是給了他一道Littlewood Conjecture，期望他在蜜月途中解決。不太清楚當時廖老師有沒有解決了這問題，但他數學研究成果豐碩，最終獲講座教授職銜。
一段小小的回憶。有一次和潘耀東同學解一條問題，其中要計算一個積分，一時未能計出。廖老師是教分析的，當然對積分很熟，於是去請教他，還以為他會推演給我們看。怎料他不慌不忙，從抽屜拿出一本積分表（今天可能是Derive, Mathematica或者Mathway之類），並說這本書包羅萬有。我們當時有點錯愕，本來以為可以目睹老師使出什麼integration by parts等技巧表演一下。
廖老師相當幽默。有一次閑談中，我們說讀中學時，經常看台灣陳明哲的小書。他說，希望他不是壞人吧！
和廖老師的點點滴滴，仍記在心，祈願他安息。
黃毅英（數學系B.A., 1977；M.Phil., 1981）
2023年4月3日
It saddened my heart to hear about this. Prof Liu (恩師) was amazing human being, an amazing teacher, and an amazing mentor who always motivated and supported me to give my best. All the lessons he taught me will be with me always. I am fortunate to have been his student.
Please send my sincerest condolences to Prof. Liu's family. Also, please let me know if there will be any memorial event for Prof. Liu and I would like to help if possible.
Stephen CHOI
April 1, 2023
Prof. Liu and Prof. Au-Yeung were like two pillars for the Dept at that time. It is sad to hear the news.
Raymond CHAN
March 31, 2023
I am very much saddened to learn that Professor Ming-Chit Liu has passed away. He has always been a most friendly colleague to myself and to all of the Department, and has been in touch with us every now and then after his retirement. He will be very much missed by all of us. The remembrance of his kindness and his most rigorous scholarship will always stay with us.
Ngaiming MOK
March 26, 2023
I learned from Mrs. Liu this morning via text message that Professor Ming-Chit Liu (廖明哲) passed away yesterday (Friday) around 3am Pacific Time. I vividly remember Professor Liu taught me Complex Analysis more than 40 years ago and he was passionate in doing research in number theory.
Mrs. Liu lives in Los Angeles area. I visited them on September 13, 2019 and had dinner with them (photo attached). It was an enjoyable dinner and Professor Liu’s mind was still very sharp. I chatted with Mrs. Liu a couple of months ago and learned that Professor Liu’s health condition deteriorated over the last couple of years.
Professor Liu was kind and friendly. He will be greatly missed.
Tin-Yau TAM
March 25, 2023