Jimira. Deng Delin is a famous mathematician. His main activity was in1the first half of the 9th century. His father is a French official and his mother is from Belgium. 18 13 was admitted to the Polytechnic University of Paris, 18 14 was wounded in the anti-French war against Napoleon, and 18 17 became a Dutch citizen. He has made great achievements in algebra, probability theory and stereo projection, and put forward the famous dandelion double-sphere theorem (used to prove the properties of conic curves) and dandelion-Graff method (used to find approximate solutions of equations). 1825 was elected as an academician of the Royal Academy of Sciences in Brussels.