On this day, 76 years ago, April 18, 1949 (March 21, 1949 in the lunar calendar), American mathematician Pafferman was born in Washington. On April 18, 1949, the mathematician Feffman was born in Washington, USA. In 1973, Feverman discovered that the convergence problem of trigonometric series was closely related to the two unrelated fields of singular integral operators, which promoted the development of the entire field; he also worked on partial differential equations and multiple complex variables. Important contributions to the theory of functions. For this reason, he won the Fields Medal, the highest award in the field of mathematics, in 1978, when he was under the age of 30.