Carl Einar Hille (28 June 1894 – 12 February 1980) was an American mathematics professor and scholar. Hille authored or coauthored twelve mathematical books and a number of mathematical papers.

Early life and education

Hille was born in

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

. His parents were both immigrants from Sweden who separated before his birth. His father, Carl August Heuman, was a civil engineer. He was brought up by his mother, Edla Eckman, who took the surname Hille. When Einar was two years old, he and his mother returned to

Stockholm Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately ...

. Hille spent the next 24 years of his life in Sweden, returning to the United States when he was 26 years old. Hille entered the

Stockholm University Stockholm University (SU) () is a public university, public research university in Stockholm, Sweden, founded as a college in 1878, with university status since 1960. With over 33,000 students at four different faculties: law, humanities, social ...

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''.

Career

In 1919 Hille was awarded the Mittag-Leffler Prize and was given the right to teach at the Stockholm University. He subsequently taught at

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

Princeton University Princeton University is a private university, private Ivy League research university in Princeton, New Jersey, United States. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial ...

Stanford University Leland Stanford Junior University, commonly referred to as Stanford University, is a Private university, private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth ...

and the

University of Chicago The University of Chicago (UChicago, Chicago, or UChi) is a Private university, private research university in Chicago, Illinois, United States. Its main campus is in the Hyde Park, Chicago, Hyde Park neighborhood on Chicago's South Side, Chic ...

. In 1933, he became an endowed professor of mathematics in the Graduate School of

Yale University Yale University is a Private university, private Ivy League research university in New Haven, Connecticut, United States. Founded in 1701, Yale is the List of Colonial Colleges, third-oldest institution of higher education in the United Stat ...

, retiring in 1962. Hille's main work was on

integral equation In mathematical analysis, integral equations are equations in which an unknown function appears under an integral sign. In mathematical notation, integral equations may thus be expressed as being of the form: f(x_1,x_2,x_3,\ldots,x_n ; u(x_1,x_2 ...

s, differential equations,

special function Special functions are particular mathematical functions that have more or less established names and notations due to their importance in mathematical analysis, functional analysis, geometry, physics, or other applications. The term is defined by ...

Dirichlet series In mathematics, a Dirichlet series is any series of the form \sum_^\infty \frac, where ''s'' is complex, and a_n is a complex sequence. It is a special case of general Dirichlet series. Dirichlet series play a variety of important roles in anal ...

and

Fourier series A Fourier series () is an Series expansion, expansion of a periodic function into a sum of trigonometric functions. The Fourier series is an example of a trigonometric series. By expressing a function as a sum of sines and cosines, many problems ...

. Later in his career his interests turned more towards

functional analysis Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (for example, Inner product space#Definition, inner product, Norm (mathematics ...

. His name persists among others in the

Hille–Yosida theorem In functional analysis, the Hille–Yosida theorem characterizes the generators of strongly continuous one-parameter semigroups of linear operators on Banach spaces. It is sometimes stated for the special case of contraction semigroups, with the ...

. Hille was a member of the

London Mathematical Society The London Mathematical Society (LMS) is one of the United Kingdom's Learned society, learned societies for mathematics (the others being the Royal Statistical Society (RSS), the Institute of Mathematics and its Applications (IMA), the Edinburgh ...

and the

Circolo Matematico di Palermo The Circolo Matematico di Palermo (Mathematical Circle of Palermo) is an Italian mathematical society, founded in Palermo by Sicilian geometer Giovanni B. Guccia in 1884.

. Hille was president of the

American Mathematical Society The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, ...

(1947–48) and was the Society's Colloquium lecturer in 1944. He received many honours including election to the

United States National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...

(1953) and the

Swedish Royal Academy of Sciences The Royal Swedish Academy of Sciences () is one of the royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for promoting natural sciences and mathem ...

. He was awarded by Sweden with the

Order of the Polar Star The Royal Order of the Polar Star (Swedish language, Swedish: ''Kungliga Nordstjärneorden''), sometimes translated as the Royal Order of the North Star, is a Swedish order of chivalry created by Frederick I of Sweden, King Frederick I on 23 F ...

Personal life

Hille was married to Kirsti Ore Hille (1906–2001) in 1937, sister of Norwegian mathematician

Øystein Ore Øystein Ore (7 October 1899 – 13 August 1968) was a Norwegian mathematician known for his work in ring theory, Galois connections, graph theory, and the history of mathematics. Life Ore graduated from the University of Oslo in 1922, with a ...

. They had two sons, Harald and

Bertil Hille Bertil Hille (born October 10, 1940) is an Emeritus Professor, and the Wayne E. Crill Endowed Professor in the Department of Physiology and Biophysics at the University of Washington. He is particularly well known for his pioneering research on ce ...

Works

*with Ralph Phillips
''Functional Analysis and Semi-Groups.''
1948, 1957. *''Analytic Function Theory.'' 2 vols., 1959, 1964. *''Analysis.'' 2 vols., 1964, 1966. *''Lectures on Ordinary Differential Equations.'' 1969. *''Methods in Classical and Functional Analysis.'' 1972. *''Ordinary Differential Equations in the Complex Domain.'' 1976. *''In Retrospect.'' Mathematical Intelligencer, Vol.3, 1980/81, No.1, pp. 3–13.

References

Other sources

* * *

External links

* {{DEFAULTSORT:Hille, Einar 1894 births 1980 deaths 20th-century American mathematicians American mathematical analysts American people of Swedish descent Members of the United States National Academy of Sciences Order of the Polar Star Stockholm University alumni Presidents of the American Mathematical Society Members of the Royal Swedish Academy of Sciences