Lars Edvard Phragmén

Lars Edvard Phragmén ( born September 2, 1863 in Örebro, † March 14, 1937 in Stockholm) was a Swedish mathematician who worked on Analysis.

Life and work

Lars Phragmen was the son of a teacher and studied in Uppsala and Stockholm. Even as a student he published his first works in 1883 and became assistant to Gösta Mittag-Leffler in Stockholm, who used him as editor for its journal Acta Mathematica. He found, for example, an error in the price - famous work of Henri Poincaré on the three-body problem that had to be rewritten then. In 1889 he graduated from the University of Uppsala and Stockholm in 1890 was a lecturer and from 1893 professor at the university as a successor to the late 1891 Sofia Kovalevskaya. In 1903, he instead took a job at the Royal inspection of insurance companies, which he became director in 1904. In 1908 he became director of the insurance company " Allmänna Lifförsakringsbolaget ".

Phragmén dealt primarily with function theory, where he proved sentences from Phragmen - Lindelöf type on upper bounds for the sums of holomorphic functions (with restrictions on their growth) in unbounded domains ( such as stripes in the complex plane ). The first version was from him alone, he proved a stronger version in 1908 with Ernst Lindelöf ( Acta Mathematica Bd.31 ). He also worked on insurance mathematics and theory of elections (where he was even in a Swedish national committee on election procedures).

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