NEUROSURGICAL FOCUS Neurosurg Focus 41 (1):E11, 2016 Chen Jingrun, China’s famous mathematician: devastated by brain injuries on the doorstep to solving a fundamental mathematical puzzle Ting Lei, MD,1 Evgenii Belykh, MD,1 Alexander B. Dru, BA,2 Kaan Yagmurlu, MD,1 Ali M. Elhadi, MD,1 Peter Nakaji, MD,1 and Mark C. Preul, MD1 1Department of Neurosurgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix; and 2University of Arizona College of Medicine, Tucson, Arizona Chen Jingrun (1933–1996), perhaps the most prodigious mathematician of his time, focused on the field of analytical number theory. His work on Waring’s problem, Legendre’s conjecture, and Goldbach’s conjecture led to progress in ana- lytical number theory in the form of “Chen’s Theorem,” which he published in 1966 and 1973. His early life was ravaged by the Second Sino-Japanese War and the Chinese Cultural Revolution. On the verge of solving Goldbach’s conjecture in 1984, Chen was struck by a bicyclist while also bicycling and suffered severe brain trauma. During his hospitalization, he was also found to have Parkinson’s disease. Chen suffered another serious brain concussion after a fall only a few months after recovering from the bicycle crash. With significant deficits, he remained hospitalized for several years with- out making progress while receiving modern Western medical therapies. In 1988 traditional Chinese medicine experts were called in to assist with his treatment. After a year of acupuncture and oxygen therapy, Chen could control his basic bowel and bladder functions, he could walk slowly, and his swallowing and speech improved. When Chen was unable to produce complex work or finish his final work on Goldbach’s conjecture, his mathematical pursuits were taken up vigor- ously by his dedicated students. He was able to publish Youth Math, a mathematics book that became an inspiration in Chinese education. Although he died in 1996 at the age of 63 after surviving brutal political repression, being deprived of neurological function at the very peak of his genius, and having to be supported by his wife, Chen ironically became a symbol of dedication, perseverance, and motivation to his students and associates, to Chinese youth, to a nation, and to mathematicians and scientists worldwide. http://thejns.org/doi/abs/10.3171/2016.2.FOCUS1595 Key WORds brain trauma; Chen Jingrun; Chinese Cultural Revolution; Goldbach’s conjecture; history of neurosurgery; Parkinson’s disease HEN Jingrun (Fig. 1), one of the world’s greatest ed next announcement to the scientific and mathematics mathematicians, focused on the field of analytical communities was to be a full solution of Goldbach’s con- number theory. Although he made significant ad- jecture, but an unfortunate series of brain injuries altered vancementsC on Waring’s problem (Edward Waring, 1736– his life and substantially affected the science of mathemat- 1798) and Legendre’s conjecture (Adrien-Marie Legen- ics and Chinese education. dre, 1752–1833), he is best known for “Chen’s Theorem,” a significant step in his work on the search for a solution to Goldbach’s conjecture, posited by the German (Prussian) Chen’s Early Life mathematician Christian Goldbach (1690–1764). In 1966 Chen Jingrun was born on May 22, 1933, in Fuzhou, and 1973, Chen published two papers to explain that every Fujian Province, China, during a period of Chinese civil sufficiently large even integer can be written as the sum war. His father, Chen Yuanjun, was a post office clerk and of a prime and a semiprime.7,8 Chen’s work proved to be his mother cared for the family. Chen’s family consisted a milestone in the study of Goldbach’s conjecture, one of of 12 children, only 6 of whom currently survive. Chen the oldest unsolved mathematical problems, and in num- was the third child of his family, which lived on a meager ber progression theory in general. Chen’s anxiously await- income. Although poor, Chen’s parents sought to provide SUBMITTED February 27, 2015. ACCEPTED February 23, 2016. INCLUDE WHEN CITING DOI: 10.3171/2016.2.FOCUS1595. ©AANS, 2016 Neurosurg Focus Volume 41 • July 2016 1 Unauthenticated | Downloaded 10/08/21 03:20 AM UTC T. Lei et al. him significant traumatic emotional stress; Chen often spoke of being plagued by lifelong panic attacks and flash- backs to these events. It was not until September 9, 1945, that the Japanese troops in China (excluding Manchuria) formally stopped their military actions in the region. Chen’s childhood continued to be a struggle, even in the relative sanctuary of elementary school. He was fre- quently bullied and beaten by classmates who picked on him because of his thin, weak stature. As if life was not hard enough, Chen lost his mother in 1947 to tuberculosis when he was 13 years old. Chen began to find solace in his studies, particularly mathematics, where he was happiest when working on tedious algebraic equations. After the occupation ended, Chen returned to Fuzhou with his family and started his formal education at Sanyi Middle School. In 1948, Chen was admitted to Fuzhou Ying hua High School. Here, he met his mathematics teach- er, Shen Yuan, who also was a director of the Aviation De- partment of Tsinghua University. Shen was a knowledge- able and passionate teacher known to mix his teachings with concrete applications to foster interest and apprecia- tion for the esoteric topics covered in his class. One day, Shen lectured on a famous number theory problem in his class called Goldbach’s conjecture. Chen recounted his teacher’s vivid description of the significance of the prob- lem: “Mathematics is the science of the queen, number theory is the crown of mathematics, and Goldbach’s con- jecture is the pearl on the crown.” Playfully, Shen told his students that he dreamt that one of them would prove the conjecture. Everyone laughed except Chen. On December 18, 1989, Chen published a memoir for The Daily Worker FIG. 1. Chen Jingrun (May 22, 1933–March 19, 1996) during his early newspaper and stated, “I did not laugh, did not dare to academic years. laugh. I was worried my classmates would know my vi- sion. But I never forgot this lesson to always remember the pearl on the crown and to never forget my aspirations or and instill the traditional strong tenets of perseverance in ideals.”22 all aspects of life, as they struggled to send their children Goldbach’s conjecture, one of the oldest and most fa- to school and obtain even basic health care.9 mous unsolved problems in number theory and mathemat- On July 7, 1937, war erupted with the Chinese War of ics, was created by Goldbach, and proposed in a series of Resistance against Japan, also known as the Second Sino- letters in June 1742 to Leonhard Euler (Fig. 2). The Gold- Japanese War. By October 26, 1937, the invading Japanese bach conjecture states simply that all positive even inte- army had advanced to occupy the Golden Gate after mov- gers of 4 or more can be expressed as the sum of 2 primes. ing across the Strait of Taiwan in a prelude to the inva- The set of integers are numbers that can be written with- sion of Fujian. At that time, Chen’s father, Chen Yuanjun, out a fractional component, consisting of zero, the natural was deployed to be a director of the Sanyuan County post numbers, and the additive inverses of natural numbers. A office, which was set up in an old temple in the nearby prime number is a natural number greater than 1 that has mountains. no positive divisors other than 1 and itself. For example, 3 The next 8 years in Fuzhou were marked by the hor- is a prime number because its only positive divisors are 1 rors of unrelenting conflicts and foreign military occupa- and 3; 4 is not a prime number because 4 has 1, 2, and 4 as tion. On April 21, 1941, and September 27, 1944, Japan positive divisors, not just 1 and 4. made aggressive moves in the Fujian Province that were On June 7, 1742, Goldbach wrote to Euler proposing characterized by multiple bombing campaigns that rav- that every integer that can be written as the sum of 2 aged the civilian populace. These raids also resulted in primes can also be written as the sum of as many primes vast destruction of public and personal property and the as one wishes, until all terms are units. Goldbach then pro- enslavement of survivors. Natives who could escape the posed a second conjecture in the margin of his letter, that concentration camps established for survivors fled to the every integer greater than 2 can be written as the sum of 3 mountains where Chen lived. Thousands of refugees were primes. He considered 1 to be a prime number, a conven- quickly followed by the Japanese soldiers, and this haven tion subsequently abandoned. The 2 conjectures are now was soon taken over by the Japanese, who interrogated and known to be equivalent, but this did not seem to be an is- tortured most of the inhabitants. The horrific memories sue at the time. A modern version of Goldbach’s marginal and sights that Chen experienced as a young child caused conjecture states that every integer greater than 5 can be 2 Neurosurg Focus Volume 41 • July 2016 Unauthenticated | Downloaded 10/08/21 03:20 AM UTC China’s famous mathematician Chen Jingrun Chen’s Academic Life In 1949, Chen (Fig. 3 left) was admitted to the Math- ematical Physics Department of Xiamen University.