Ye Yanqian was physically weak and introverted since childhood, and received strict family education. Especially when he was studying in junior high school, he lived with his grandfather day and night. The noble character and hard-working spirit of the old man left an unforgettable impression on him. By the time he graduated from junior high school, he had basically developed the habit of being upright, cautious and studying hard. He wanted nothing more than that. Determined to grow up and become a mathematician.

In 1937, when War of Resistance against Japanese Aggression broke out, he lived in the countryside for three years. During this period, the whole family moved back to Kaihua, leaving only his father to continue practicing medicine in Quzhou to make a living. In 194, he won the first place in the provincial examination for Chinese language when he graduated from high school. In the autumn of the same year, he was admitted to the Mathematics Department of Longquan Branch of Zhejiang University and finished his second grade in the summer of 1942. He devoted himself to studying books. He was among the best in all subjects except English. When he recalled this period of life, he deeply regretted that he didn't take advantage of his superior family conditions to learn more about China history and medicine.

In the autumn of 1942, the Japanese invaders opened zhejiang-jiangxi railway, which separated Quzhou, Kaihua and Longquan, making it difficult for him to return home. Because there were no third or fourth grades in Longquan Branch of Zhejiang University, A few students transferred to other colleges and universities in southern Zhejiang and Fujian. Ye Yanqian went to the headquarters of Zhejiang University in Meitan, Guizhou with a large number of students from Longquan via Fujian, Jiangxi, Guangdong, Hunan and Guangxi provinces. On the way, they sometimes walked, sometimes took a boat, sometimes took a freight truck (then people called it a "yellow croaker car"), sometimes took a train, and stopped and stopped. After arriving in Nanping, Fujian, their accommodation was either a primary school or a church. The large group had to disperse and find their own way out. At this time, only six people were left with Ye. During the journey, they suffered a lot from drift from place to place and traveled long distances. When they reached their destination, it took more than two months! These young people under the age of 2, far away from their hometown and relatives, have gone through all kinds of hardships and traveled thousands of miles in Qian Shan. I don't know when they will be reunited with their families after this parting. What kind of power supports them to finish this long and arduous journey? Ye Yanqian said: "At that time, the mathematics department of Zhejiang University was first-class in China. In order to realize my wish, I had to go to Meitan!"

During the four years of studying and working in Meitan from 1942 to 1946, he had both pains and joys. At that time, there were less than 3 students in the second, third and fourth grades of the Department of Mathematics and all the teachers. In addition to teaching and scientific research activities, all of them had to go out for an outing for one day every spring and autumn. After returning, they went to a restaurant opened by people in Guangdong, Sichuan or Hunan for dinner. On holidays, Chen Jiangong, Su Buqing, Xu Ruiyun, Jiang Shuomin, Lu Qingjun and other teachers always invite single teachers and students from all departments to their homes for the holidays. After 1943, the family members of classmate Yu Wangsen also came to Meitan, and they treated Ye Yanqian like brothers, which added a little warmth to him in a foreign land.

In the third and fourth grades of college, he didn't study hard, except for his daily homework and some exams. Swimming and mountain climbing. Those who are interested in the courses they study every semester spend more time, while those who are not interested only want to pass. In the summer of 1944, Ye Yanqian stayed in school as a teaching assistant after graduating from university. His homesickness was aggravated by his life in a foreign land for more than two years, which made him unable to concentrate on scientific research and often indulge in ancient poetry. At that time, there was a primary school next to the dormitory. The primary school music teacher often taught his students to sing a song called "Light Jiangnan" The beautiful piano music accompanied by the immature songs of the children fascinated the wanderer who was far away from his hometown. More than 4 years later, he encountered a similar situation in Nanjing University in 1986. Although he was not singing that song, the piano music touched the scene and made Ye Yanqian, who had entered the old age, feel deeply moved. He wrote a word entitled "Smelling the piano across the lane" to commemorate the past:

The title of the song is faint in the south of the Yangtze River, but the return of the south of the Yangtze River has not been achieved.

Stubborn and lonely, Jinling Resort has nurtured new people.

When I look back, I find tears in my eyes.

During his stay in Zhejiang University, Professor Chen Jiangong had high hopes. In the fourth grade, Chen Jiangong put Paley and Wiener on Fu Liye. I hope he can carry out research work in this field. Shortly after the Japanese surrender in 1945, Chen Jiangong and Su Buqing went to Taiwan Province Province to take part in the work of accepting Taiwan Province University, which interrupted his guidance. In addition, he was not interested in Fourier analysis, so he went to look for some books and papers to read. His first paper studied not Fourier series, but commutative subgroups. Later, Chen Jiangong transferred it to Professor Duan Xuefu for review. It was recommended to Bull. Amer. Math in the United States and published in 1948. < P > In the summer of 1946, Ye Yanqian returned to Zhejiang with the teachers and students of Zhejiang University. He returned to his hometown where he had been away for four years to reunite with his family, but he did not see his sister's heir badge. It turned out that she died of typhoid fever more than a year ago. Her death was inseparable from the hard life and lack of medicine in the rural areas of China under the Japanese invaders. He also failed to get timely medical treatment from his father. His sister's death made him very sad. In the autumn of this year, he continued to work as a teaching assistant in the Department of Mathematics of Zhejiang University. In addition to teaching calculus, he did not carry out scientific research. In the autumn of 1947, at his request, Chen Jiangong introduced him to the Institute of Mathematics of Shanghai Academia Sinica. At that time, although Chen was reluctant to let him leave Zhejiang University, he agreed to his request. Chen Jiangong was deeply moved by his generosity. He is an assistant in Chen Jiangong. Soon Chen went to Princeton Research Institute in the United States, so he turned to attend the Topology Seminar hosted by Professor Chen Shengshen, and started from scratch with a dozen young people who graduated from universities for less than three years. During his one and a half years in the Institute of Mathematics, he suffered from severe neurasthenia and his work efficiency was extremely poor. In 1947, he wrote a small paper, but in 1948, he made no achievements. Chen Shengshen is also very concerned about him. His teacher Wang Fuchun, who was studying at Zhejiang University, died in Nanchang, Jiangxi, and the bad news spread to Shanghai. Chen Shengshen immediately asked him to write a short essay in memory of Wang, which was published in Science magazine. Chen Shengshen also personally revised the paper on "Geometry of Numbers" for him and sent it to Professor Mahler of Manchester University, England, who recommended it. It was published in Journal. London. Math. SOC in 1948. In the same year, Chen Shengshen actively recommended him to apply for the British Cultural Fund and strive to study in the UK. Unfortunately, he failed to do so because of his poor English listening and speaking skills.

In the past few years after graduating from college, he was depressed and depressed, except for physical factors. It had a lot to do with the government corruption, soaring prices and poor people at that time, which made him unable to see the future of the country and individuals. Even so, when he was in Meitan in 1945, he also went to attend the German teacher three times a week-his highly respected foreign teacher, Mr. De Mengtie, gave a Russian class for fourth-grade students, reaching the level of barely reading Russian math books. During this period, he wrote a poem expressing his feelings by taking advantage of the scenery: "Don't sneer at the water trickling down." The Yangtze River is still rolling. "Ambition overflows between the lines. Later, he read mathematics books and papers in Beijing, Shanghai and Hangzhou for two or three years, which broadened his knowledge.

At the beginning of 1949, the former Institute of Mathematics moved to Taiwan Province. After three months in Quxian, he returned to Zhejiang University to replace the teaching assistant of Yueminyi. After the summer vacation, he was hired as a lecturer. It was not until September 1952 that he was transferred from Zhejiang University to Nanjing University. The founding of the People's Republic of China made him see the bright future of the country and individuals, and his spirit was greatly uplifted. From then on, he never had time to play cards and chess. In the first two or three years, he was busy with class affairs and political movements. After marriage, two sons were born, and a lot of housework was added. However, he still participated in the translation of Advanced Mathematics Course written by smirnoff. In order to introduce this excellent textbook to the mathematics field in China as soon as possible, most of his translation work was completed in the severe winter and hot summer nights during the winter and summer vacations. After Professor Zhang Sucheng came back from England, he and Jin Fulin attended a topology seminar hosted by Zhang and read many papers by J.H.C.Whitehead and H.Whitney During these two years, his husband and wife lived in Zhejiang. His aunt accompanied his grandfather to live in the Provincial Museum of Literature and History, and his second brother Yanfu studied in the Agricultural College of Zhejiang University. Later, his sister Si Mao was admitted to Zhejiang Medical University, and more than half of his family gathered in Hangzhou. Every Sunday, he visited each other or got together by appointment. Sometimes he accompanied his grandfather to visit Mr. Ma Yifu (an old friend of his grandfather's) in Jiangzhuang. All this made him enjoy the family fun again after living a single life for many years. This is undoubtedly one of the reasons that prompted him to work hard.

After he arrived at Nanjing University in the autumn of 1952, he was entrusted by the publishing house to revise the first volume of Calculus Course, the original work of Fichkin Goelz translated by Yang Maoliang. It took a lot of time. In addition, he also completed three other foreign language books. After 1954, he gradually realized that China should have its own strong mathematical research team. Determined to make a contribution to this, I deeply felt that I should not stop doing translation work. At that time, Professor Huang Zhengzhong invited him to join the Geometrical Topology Group. However, after summing up the experience of the past ten years, he realized that his computing ability and abstract thinking ability were not strong enough, and he was not confident to continue studying topology. Just then, the Institute of Mathematics of the Chinese Academy of Sciences hosted the summer differential equation workshop for the first time in 1954 to advocate that it was very weak in China. And it is a very important subject in integrating mathematical theory with practice, so he went to Beijing to attend a lecture. The introductory knowledge of topology obtained in the original mathematics made him interested in the qualitative theory of ordinary differential equations. He changed the state of wandering in the direction of scientific research in the past and made up his mind to persist in deepening in one field from now on. Since then, he has been studying hard for three or four years despite years of neurasthenia, and finally he was pleasantly surprised to find that although modern mathematics has developed rapidly in many aspects, In particular, the qualitative theory of real polynomial system is rarely discussed. In 1955, Petrovsky and others' paper aroused his great interest in quadratic polynomial system. At that time, although the main conclusions and proofs of this paper were not found to be wrong, he believed that from the epistemological point of view, plane real quadratic polynomial system is the simplest case of nonlinear differential equation and should be paid attention to. From the practical point of view, What is more important than Hilbert's 16th problem is to make a concrete investigation of general real quadratic systems, study the geometric properties and relative positions of trajectories, and then classify the equations, and study the existence and number of limit cycles and the global topological structure of trajectories one by one. Once the above work is completed, Hilbert's 16th problem will be naturally solved when n=2. Interestingly, In 1979, three scholars in China cited counterexamples to the conclusion of Petrovsky's paper. Counterexamples are one of many important achievements obtained by this method.

For more than 3 years, with the efforts of mathematicians in China and the Soviet Union, the qualitative theory of real quadratic system has achieved fruitful results (these works should have been done by people from the end of 19th century to the beginning of 2th century), which has been recognized internationally. Ye Yanqian's monograph The Theory of Limit Cycles was published by Shanghai Science and Technology Publishing House, and was included in the "Modern Mathematics Series". In 1982, it was revised and supplemented by eight scholars, which included most of the important achievements before the 198s, and was reprinted in 1984. In 1986, the American Mathematical Society entrusted Professor Lu Zhiyang to translate this book into English for publication. In 1987, The July issue of Bull. Amer. Math. SOC published a book review of this book, which made a high evaluation. In October 1986, he gave the English version of this book to his teacher Su Buqing. Su Lao was very happy, and when a reporter was present, Su Lao immediately took a photo with him with the book.