Math Quartet Joins Forces on Unified Theory

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Friday, Jan 8, 2016

A new breakthrough that bridges number theory and geometry is just the latest triumph for a close-knit group of mathematicians.

One of the first collaborations Xinyi Yuan and Wei Zhang ever undertook was a trip to the Social Security office. It was the fall of 2004 and the two of them were promising young graduate students in mathematics at Columbia University. They were also friends from their college years at Peking University in Beijing. Yuan had come to Columbia a year earlier than Zhang, and now he was helping his friend get a Social Security number. The trip did not go well.

“We went there, and we were told that some document of Wei’s was missing and that he couldn’t do it at that time,” Yuan recalled.

That failed attempt was one of the few unsuccessful team efforts the two have undertaken since coming to the U.S. Zhang, who is now a professor at Columbia, and Yuan, now an assistant professor at the University of California, Berkeley, are members of an unofficial quartet of Chinese mathematicians who have been friends since their undergraduate days at Peking University in the early 2000s and now hold positions in some of the best mathematics departments in the world.

That a number of elite mathematicians would come out of the same class at a top university is unusual, but not unprecedented. The most recent example is Manjul Bhargava, Kiran Kedlaya and Lenny Ng, freshman classmates at Harvard University who went on to become distinguished mathematicians. They remain good friends and all traveled to Seoul in 2014 when Bhargava won the Fields Medal.

What’s unusual about the group formed by Zhang, Yuan and their two friends is the degree to which they continue to collaborate and the extraordinary amount of successes that they’ve had.