Einar Hille

Einar Hille (1894 to 1980) was an American mathematician who worked on analysis and functional analysis. Born in New York City to Swedish parents, he was raised in Stockholm, studied at Stockholm University, began research there with Marcel Riesz on conformal mappings, took his doctorate in 1918 and won the Mittag-Leffler Prize in 1919. He returned to the United States in 1920, taught at Harvard and Princeton, and from 1933 until he retired in 1962 held a chair at Yale University. His main work concerned integral equations, differential equations, special functions, Dirichlet series and Fourier series, and later functional analysis, and his name lives on in the Hille-Yosida theorem. He wrote Functional Analysis and Semi-Groups with Ralph Phillips and several texts on analysis and differential equations. He served as president of the American Mathematical Society and was elected to the United States National Academy of Sciences in 1953.