At the end of the Cultural Revolution, in 1978, he enrolled as a mathematics student at Peking University. A brilliant student, he moved to the United States in 1985 on a scholarship to pursue a doctorate at Purdue University in Indiana. His dissertation, completed in 1991, concerned the Jacobian conjecture : this involves polynomials in several variables and, more specifically, their inversion. Shy and dissatisfied with his results, he published no papers and received no encouragement from his doctoral adviser. The conjecture remains unsolved to this day; it is one of the most important open problems in algebraic geometry.
After completing his dissertation, he was unable to find a teaching position and took a variety of jobs: delivery driver, accountant for a fast-food chain… In 1999, Kenneth Ira Appel (1932–2013) – known for proving the four-color theorem in 1976 with Wolfgang Haken (born in 1928) – was chair of the mathematics department at the University of New Hampshire and offered him a position as a lecturer there. This left him time to "keep thinking," as he likes to put it. Since achieving his spectacular result (see "What happened next…"), he has been appointed a professor at the University of California, Santa Barbara.
A first step towards the twin prime conjecture
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The twin prime conjecture states that there are infinitely many twin primes—that is, pairs of prime numbers differing by 2, such as 17 and 19. The conjecture seems to have been formally stated for the first time in 1849 by the French mathematician Alphonse de Polignac (1826–1863).
