Ye Li's main contribution to mathematics is astrophysics (the method of setting unknown parallel equations), which is used to study the properties of inscribed circle and circumscribed circle of right triangle. Together with Yang Hui, Qin and Zhu Shijie, they are also called "the four great mathematicians of Song and Yuan Dynasties".

Extended data:

Ye Li's research interests are very extensive, involving mathematics, literature, history, philosophy, medicine and so on. His research fields include social science and natural science. When he lived in seclusion in Tongchuan, Yan county, he got a copy of the arithmetic of his predecessors, which contained the theory of nine quantities, with the emphasis on Pythagoras compatibility. Ye Li's mathematical research in Tongchuan mainly focuses on Heaven. At this time, although astrology has been produced, it is still immature.

Inspired by the theory of nine contents, he studied the Pythagorean inclusion circle as a system, and discussed the problem of finding the diameter of the circle by celestial technique under various conditions. After ten years of research, the round sea mirror was finally completed in 1248. At this time, Ye Li is 56 years old. He spent many years working hard to bring celestial science to a fairly perfect level. It was a first-class mathematical work in the world at that time, which attracted the attention of foreign scholars and was published as a book.

Baidu Encyclopedia-Ye Li (mathematician, writer and poet in Jin and Yuan Dynasties)