「點滴」專欄：夏志宏：喜歡唱歌和垃圾食品的數學家文蘭

知識 03-15

文蘭（1946年3月-），數學家，北京大學教授，中國科學院院士，第三世界科學院院士

撰文 | 夏志宏

知識分子為更好的智趣生活ID：The-Intellectual

今天（作者註：3月14日）是好友文蘭院士生日。兩年前我們曾在南方科技大學召開了一個國際動力系統會議。我們趁那次機會慶祝幾位著名數學家的壽辰，在南科大招待所舉行了一個簡單、歡快的活動。這是我主持活動的講話。

參會者大多是外國人，此文是按西方習慣用英文寫的。感謝趙夢女士的中文翻譯。

I am delighted and honored to have the opportunity to host this celebration. We gather here todayto celebrate the birthdays of five great mathematicians. Professor Lan Wen for his 70th birthday and Professors Keith Burns, Konstantin Khanin, Carlangelo Liveraniand Sandro Vaienti for their 60th birthdays.

In old Chinses calendar, there are only 60 years. At year 60, it cycles back to zero. 60 means that life starts again. Today, we have one 10-year-old and four baby mathematicians. I』ll first spend a first minutes to make a few remarks about my friend of more than 30 years, Lan Wen. I』ll invite others to talk about these birthday babies. We will leave time for all of you to join us in the celebration.

I first met Lan at Northwestern in 1984, when we both began our graduate studies in dynamics. Lan was much older than 10 at the time, he was 38. I was 21. Despite of the age difference, that turned out to be the beginning of lifetime friendship. We were in the same area and we took many courses and shared many moments together.

Lan finished his Ph.D. in three years, in 1987. It』s a little embarrassing that it took me four years to finish. After a year teaching at Chicago State, Lan decided to return to China to teach at Peking University. He loved the country and became one of the first few to come back, when China was really a third world country.

Lan is a true mathematician. He was born on March 14, the Pi day. He is instrumental in building the dynamical systems research group in China. He was elected to the National Academy of Sciences of China and the Third World Academy of Sciences. He had successfully served as the President of Chinese Mathematical Society. Rumor has it that he was very reluctant to take the position, but he was elected by the committee while he went to bathroom.

Besides mathematics, Lan loves junk food and he loves singing. We had many Big Macs at McDonald』s together, particularly the year we spent in Hong Kong together, visiting Steve Smale. He said he could have three meals a day at McDonald』s! Some yearsago, Lan hosted my colleague, Professor John Franks』 visit to Beijing. After all interesting meals as one can image in Beijing, John decided to treat Lanand his family, but on one condition, Lan had to pick a restaurant. To John』s surprise, Lan said Kentucky Fried Chicken!

Lan is a very good singer. During our graduate student days, every year, Lan would sing at math department』s Christmas Party. This tradition continued when Lan』s son, Jim Wen, joined the math department as a graduate student. We look forward to the day when Lan』s grandchildren join the math department at Northwestern!

Finally, Lan is gentle and caring, he earned great respect, both in and out of mathematics, by respecting others. Lan, thank you for your friendship and happy birthday!

我很高興也很榮幸能有此機會主持本次慶宴。今天，我們齊聚一堂，共慶五位著名數學家的生日。他們分別是過七十大壽的文蘭教授、過六十大壽的Keith Burns教授、Konstantin Khanin教授、Carlangelo Liverani教授以及 Sandro Vaienti 教授。

按中國古代曆法，六十年一甲子。六十歲的生命將是一個嶄新的開始。這麼說來，今天我們有一位10歲的數學家和四位新生的數學家。我將首先用幾分鐘介紹一下與我相識愈三十年的好友文蘭，再邀請大家為四位新生寶寶們致詞。最後，我們將留下時間讓大家一起慶祝。

我第一次見到文蘭是在1984年，那年我們都剛到西北大學攻讀動力系統專業博士研究生。那時文蘭38歲，可比10歲要大不少。我那時21歲。儘管年齡上相差很大，但那卻是我們這一輩子友誼的開始。因為學的是同樣的專業，我們會一起上課，也經常一起玩耍。

文蘭用了三年時間完成了博士學業，於1987年拿到了理學博士學位。說起來慚愧，我用了四年時間才拿到博士學位。文蘭先在芝加哥州立大學教了一年書，然後決心回中國到北京大學任教。那時的中國真是一個第三世界國家，社會經濟還很落後。但文蘭深愛著這個國家，成為了回國效力的最早的那一批人之一。

文蘭是一個真正的數學家。他出生於三月十四日，即圓周率日。他積極推動了中國動力系統研究團隊的建設。他當選中國科學院院士及第三世界科學院院士。他也曾擔任過中國數學會理事長，在任期間成績突出。傳聞他本人並不想當這個理事長，但委員會成員趁他去洗手間時將他選為理事長。

除了數學，文蘭也喜歡唱歌和垃圾食品。我跟他一起去吃了很多次麥當勞的巨無霸漢堡。特別是我們一起在香港訪問 Steve Smale 的那一年。他說他可以一日三餐都吃麥當勞！幾年前，我的同事John Franks 教授訪問北大。文蘭接待了他，帶他吃遍了北京的各色美食。而後，John 決定要回請文蘭和他的家人，並讓文蘭自己選擇吃什麼。令 John 意想不到的是，文蘭說那就吃肯德基吧！

文蘭的歌唱得很好。我們在西北讀研期間，每年數學系的聖誕晚會上文蘭都會唱上一首。當文蘭的兒子小文也進入西北大學數學系讀研時，這個傳統也延續到了小文的身上。我們可以期待文蘭的孫兒孫女們也到西北大學數學系讀書的那一天！

最後，文蘭性格謙和體貼，始終以禮待人。無論在數學圈內還是圈外，他都備受尊敬，因為文蘭尊敬他人。友情似佳釀，愈久彌香。謝謝你，文蘭！生日快樂！

——2016.7.29晚南科大專家公寓1號樓宴會廳