Ernst David Hellinger (September 30, 1883 – March 28, 1950) was a German

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

Early years

Ernst Hellinger was born on September 30, 1883 in Striegau, Silesia, Germany (now

Strzegom Strzegom (german: Striegau) is a town in Świdnica County, Lower Silesian Voivodeship, in south-western Poland. It is the seat of the Gmina Strzegom administrative district (gmina). It lies approximately north-west of Świdnica, and west of th ...

, Poland) to Emil and Julie Hellinger. He grew up in Breslau, attended school and graduated from the Gymnasium there in 1902. When he was studying at the Gymnasium, he became fascinated with mathematics, due to excellent

mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

teachers at the school.

Academic career

After graduating from the Gymnasium, Ernst Hellinger entered the

University of Heidelberg } Heidelberg University, officially the Ruprecht Karl University of Heidelberg, (german: Ruprecht-Karls-Universität Heidelberg; la, Universitas Ruperto Carola Heidelbergensis) is a public research university in Heidelberg, Baden-Württemberg, ...

, but didn't complete his studies there. After Heidelberg, he studied at the

University of Breslau A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, th ...

, before completing his doctorate at the

University of Göttingen The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded ...

in 1907 with a thesis entitled ''Die Orthogonalinvarianten quadratischer Formen von unendlich vielen Variablen''. At Göttingen he worked with

David Hilbert David Hilbert (; ; 23 January 1862 – 14 February 1943) was a German mathematician, one of the most influential mathematicians of the 19th and early 20th centuries. Hilbert discovered and developed a broad range of fundamental ideas in many ...

, one of the most influential mathematicians of the 20th century. Hellinger taught at the University of Göttingen (1907–1909), the

University of Marburg The Philipps University of Marburg (german: Philipps-Universität Marburg) was founded in 1527 by Philip I, Landgrave of Hesse, which makes it one of Germany's oldest universities and the oldest still operating Protestant university in the wor ...

(1909–1914), and the University of Frankfurt (1914–1935).

Adolf Hitler Adolf Hitler (; 20 April 188930 April 1945) was an Austrian-born German politician who was dictator of Germany from 1933 until his death in 1945. He rose to power as the leader of the Nazi Party, becoming the chancellor in 1933 and the ...

came to power in Germany in 1933, and while they were in power the Nazis removed several Jewish scientists and mathematicians from German universities. Hellinger's family was Jewish, and he was removed from the faculty of the University of Frankfurt in 1936.

Later years

On November 13, 1938, Hellinger was arrested, taken to the Festhalle, and then put into

Dachau concentration camp , , commandant = List of commandants , known for = , location = Upper Bavaria, Southern Germany , built by = Germany , operated by = ''Schutzstaffel'' (SS) , original use = Political prison , construction ...

. However, his friends were able to arrange a temporary job for Hellinger at

Northwestern University Northwestern University is a private research university in Evanston, Illinois. Founded in 1851, Northwestern is the oldest chartered university in Illinois and is ranked among the most prestigious academic institutions in the world. Charte ...

Evanston, Illinois Evanston ( ) is a city, suburb of Chicago. Located in Cook County, Illinois, United States, it is situated on the North Shore along Lake Michigan. Evanston is north of Downtown Chicago, bordered by Chicago to the south, Skokie to the west, ...

in the United States. He was released from the Dachau camp after six weeks, on condition that he emigrate immediately. He joined the faculty at Northwestern University as lecturer in Mathematics in 1939. He became a U.S. citizen in 1944. Promoted to professor in 1945, he became emeritus in 1949. He died on March 28, 1950 in

Chicago, Illinois (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...

, United States.

Contributions to mathematics

Ernst Hellinger studied

integral equation In mathematics, 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,...,x_n ; u(x_1,x_2,x_3,...,x_n) ...

s, the infinite system of equations, real functions and

continued fraction In mathematics, a continued fraction is an expression obtained through an iterative process of representing a number as the sum of its integer part and the reciprocal of another number, then writing this other number as the sum of its integer ...

s. A type of integral which he introduced in his dissertation became known as "the Hellinger integral", used for defining the Hellinger distance. Hellinger distance has been used to process natural language and learning word embeddings. In addition, the Hilbert–Hellinger theory of forms in infinitely many variables profoundly influenced

mathematical analysis Analysis is the branch of mathematics dealing with continuous functions, limits, and related theories, such as differentiation, integration, measure, infinite sequences, series, and analytic functions. These theories are usually studied ...

References

External links

Biography of Ernst David HellingerNorthwestern University archivePhoto
(with

Alfréd Haar Alfréd Haar ( hu, Haar Alfréd; 11 October 1885, Budapest – 16 March 1933, Szeged) was a Kingdom of Hungary, Hungarian mathematician. In 1904 he began to study at the University of Göttingen. His doctorate was supervised by David Hil ...

Hermann Minkowski Hermann Minkowski (; ; 22 June 1864 – 12 January 1909) was a German mathematician and professor at Königsberg, Zürich and Göttingen. He created and developed the geometry of numbers and used geometrical methods to solve problems in number t ...

) at

Yeshiva University Museum The Yeshiva University Museum is a teaching museum and the cultural arm of Yeshiva University. Along with the American Jewish Historical Society, the American Sephardi Federation, the Leo Baeck Institute, New York and the YIVO Institute for Jewish ...

(NYC) * {{DEFAULTSORT:Hellinger, Ernst 1883 births 1950 deaths University of Göttingen alumni University of Göttingen faculty Northwestern University faculty 20th-century German mathematicians