Lars Phragmén

Lars Edvard Phragmén

Lars Edvard Phragmén (born September 2, 1863 in Örebro , † March 14, 1937 in Stockholm ) was a Swedish mathematician who dealt with analysis .

Live and act

Lars Phragmen was the son of a teacher and studied in Uppsala and Stockholm . As a student he published his first work in 1883 and became an assistant to Gösta Mittag-Leffler in Stockholm, who appointed him as editor for his journal Acta Mathematica. He found z. B. a mistake in the famous price work by Henri Poincaré on the three-body problem, which then had to be rewritten. In 1889 he graduated from Uppsala University and became a lecturer in Stockholm in 1890 and professor at the university from 1893 as the successor to Sofia Kowalewskaja, who died in 1891. In 1903 he instead accepted a post in the Royal Insurance Company Inspectorate, of which he became director in 1904. In 1908 he became director of the insurance company "Allmänna Lifförsakringsbolaget".

Phragmén was mainly concerned with function theory , where he proved theorems of the Phragmen-Lindelöf type about upper bounds for the amounts of holomorphic functions (with restrictions on their growth) in unbounded domains (such as strips in the complex plane). The first version came from him alone, he proved a stronger version in 1908 with Ernst Lindelöf (Acta Mathematica Vol. 31). He also worked on actuarial mathematics and the theory of elections (there he was even on a Swedish state committee on electoral procedures).

From 1889 to 1937 he was co-editor of Acta Mathematica. From 1909 he was chairman of the Swedish Society of Insurers for many years.

literature

• Lars Phragmén . In: Herman Hofberg, Frithiof Heurlin, Viktor Millqvist, Olof Rubenson (eds.): Svenskt biografiskt handlexikon . 2nd Edition. tape 2 : L – Z, including supplement . Albert Bonniers Verlag, Stockholm 1906, p. 285 (Swedish, runeberg.org ).

Web links

• Biography of Birkeland