**Hellinger** introduced a new type of integral: the *Hellinger integral *. Jointly with Hilbert he produced an important theory of forms.

- Ernst grew up in Breslau where he attended school, graduating from the Gymnasium there in 1902.
- It was at the Breslau Gymnasium that Hellinger first became fascinated in mathematics, and this was the result of an excellent mathematics teacher at the school.
- Hellinger entered the University of Heidelberg but, following the tradition in Germany at that time, he did not complete his studies at a single university but moved to several different universities during the course of his studies.
- Hellinger would keep in touch with Born and developments in quantum mechanics for much of his life.
- In Göttingen Hellinger was a student of Hilbert and, not long after he began his studies there, he was joined by Courant and Toeplitz who had been his fellow students at Breslau.
- Hellinger was awarded his doctorate by the University of Göttingen in 1907 for a thesis entitled Die Orthogonalinvarianten quadratischer Formen von unendlich vielen Variablen Ⓣ(The Orthogonallly invariant quadratic forms in an infinite number of variables).
- He introduced a new type of integral, the Hellinger integral in his doctoral thesis and, jointly with Hilbert, he produced the important Hilbert-Hellinger theory of forms.
- From Göttingen Hellinger went to Marburg where he was a Privatdozent from 1909 to 1914.
- Hellinger certainly qualified under this clause and this allowed him to keep his lecturing post in Frankfurt in 1933.
- Hellinger continued to live in Frankfurt.
- Fortunately friends were able to arrange a temporary job for Hellinger at Northwestern University at Evanston in the United States.
- Hellinger's position at Evanston throughout the war was precarious with a series of one-year appointments but he acquired American citizenship in 1944 and worked at Evanston until 1949 when he retired.
- At Frankfurt, Hellinger had continued his mathematical work on the spectral theory of Jacobi forms and continued fractions.
- Hellinger also worked on the history of mathematics and, while at Frankfurt, he wrote an important paper on James Gregory.
- At this Hellinger ...

Born and developments in quantum mechanics for much of his life. * In Göttingen Hellinger was a student of Hilbert and, not long after he began his studies there, he was joined by Courant and Toeplitz who had been his fellow students at Breslau. * Hellinger was awarded his doctorate by the University of Göttingen in 1907 for a thesis entitled Die Orthogonalinvarianten quadratischer Formen von unendlich vielen Variablen Ⓣ(The Orthogonallly invariant quadratic forms in an infinite number of variables). * He introduced a new type of integral, the Hellinger integral in his doctoral thesis and, jointly with Hilbert, he produced the important Hilbert-Hellinger theory of forms. * From Göttingen Hellinger went to Marburg where he was a Privatdozent from 1909 to 1914. * Hellinger certainly qualified under this clause and this allowed him to keep his lecturing post in Frankfurt in 1933. * Hellinger continued to live in Frankfurt. * Fortunately friends were able to arrange a temporary job for Hellinger at Northwestern University at Evanston in the United States. * Hellinger's position at Evanston throughout the war was precarious with a series of one-year appointments but he acquired American citizenship in 1944 and worked at Evanston until 1949 when he retired. * At Frankfurt, Hellinger had continued his mathematical work on the spectral theory of Jacobi forms and continued fractions. * Hellinger also worked on the history of mathematics and, while at Frankfurt, he wrote an important paper on James Gregory.

Born and developments in quantum mechanics for much of his life. * In Göttingen Hellinger was a student of Hilbert and, not long after he began his studies there, he was joined by Courant and Toeplitz who had been his fellow students at Breslau. * Hellinger was awarded his doctorate by the University of Göttingen in 1907 for a thesis entitled Die Orthogonalinvarianten quadratischer Formen von unendlich vielen Variablen Ⓣ(The Orthogonallly invariant quadratic forms in an infinite number of variables). * He introduced a new type of integral, the Hellinger integral in his doctoral thesis and, jointly with Hilbert, he produced the important Hilbert-Hellinger theory of forms. * From Göttingen Hellinger went to Marburg where he was a Privatdozent from 1909 to 1914. * Hellinger certainly qualified under this clause and this allowed him to keep his lecturing post in Frankfurt in 1933. * Hellinger continued to live in Frankfurt. * Fortunately friends were able to arrange a temporary job for Hellinger at Northwestern University at Evanston in the United States. * Hellinger's position at Evanston throughout the war was precarious with a series of one-year appointments but he acquired American citizenship in 1944 and worked at Evanston until 1949 when he retired. * At Frankfurt, Hellinger had continued his mathematical work on the spectral theory of Jacobi forms and continued fractions. * Hellinger also worked on the history of mathematics and, while at Frankfurt, he wrote an important paper on James Gregory. * At this Hellinger ...

Born 30 September 1883, Striegau, German Empire (now Strzegom, Poland). Died 28 March 1950, Chicago, Illinois, USA.

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Origin Poland

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive