Einar Hille

Carl Einar Hille (born Carl Einar Heuman; 28 June 1894 – 12 February 1980) was a Swedish American mathematician.

Hille was born in New York to Swedish immigrant parents. He was the son of Carl August Heuman, a civil engineer, and Edla Eckman. When Einar Hille was two years old his mother returned to Sweden and lived in Stockholm. Hille spent the next 24 years of his life in Sweden, returning to the United States when he was 26 years old.
Career

Hille entered the University of Stockholm in 1911. Hille was awarded his first degree in mathematics in 1913 and the equivalent of a Master's degree in the following year. He received a Ph.D. from Stockholm in 1918 for a doctoral dissertation entitled Some Problems Concerning Spherical Harmonics.

In 1919 Hille was awarded the Mittag-Leffler Prize and was given the right to teach at the University of Stockholm. He subsequently taught at Harvard University, Princeton University, Stanford University and the University of Chicago. In 1933, he became an endowed professor on mathematics in the Graduate School of Yale University. Hille was a member of the London Mathematical Society and the Circolo Matematico di Palermo. Hille served as president of the American Mathematical Society (1937–38) and was the Society's Colloquium lecturer in 1944. He received many honours including election to the United States National Academy of Sciences (1953) and the Royal Academy of Sciences of Stockholm. He was awarded by Sweden with the Order of the Polar Star.

Hille's main work was on integral equations, differential equations, special functions, Dirichlet series and Fourier series. Later in his career his interests turned more towards functional analysis. His name persists among others in the Hille–Yosida theorem.

Hille was married to Kirsti Hille (née Ore), sister of Norwegian mathematician Øystein Ore, and had two sons, Harald and Bertil Hille. He died in La Jolla, California.
References

Yosida, K. (1981). "Some aspects of E. Hille's contributions to semigroup theory". Integral Equations Operator Theory 4 (3): 311–329. doi:10.1007/BF01697968.
Benson, Adolph B.; Hedin, Naboth (1969). Swedes In America. New York: Haskel House.

External links

O'Connor, John J.; Robertson, Edmund F., "Einar Hille", MacTutor History of Mathematics archive, University of St Andrews.