Piers Bohl

from Wikipedia, the free encyclopedia

Piers Bohl (born October 11th July / October 23rd  1865 greg. In Walk ; † December 25th 1921 in Riga ) was a Livonian mathematician who dealt with almost periodic functions , celestial mechanics and differential equations .

Life

Piers Bohl was born as the son of a German-Baltic merchant in Walk and went to the Livonian knightly high school in Fellin . From 1884 he studied mathematics in Dorpat (among other things with the astronomer Anders Lindstedt ). There he received a gold medal in 1886 for his work Theory and Application of the Invariants of Linear Differential Equations and graduated in 1887. After that he worked as a teacher. In 1893 he received his doctorate in Dorpat (master's dissertation: on the representation of functions of a variable by trigonometric series with several arguments proportional to a variable ) and taught at the Baltic Polytechnic in Riga from 1895 , at that time under Russian rule (he also taught in Russian). In 1900 he completed his habilitation in Dorpat with Adolf Kneser (doctoral dissertation: On some differential equations of general character applicable to mechanics ) and became a professor in Riga. During the First World War, the university was evacuated to Moscow, where Bohl spent three grueling years. In 1919, during the brief period of Latvia's independence, Bohl returned to the university in Riga, but died of a stroke two years later.

Bohl was the first to investigate (in his Magister dissertation from 1893) quasi-periodic functions, which were rediscovered in 1903 by the French astronomer Ernest Esclangon (from whom the name comes from) and which were later examined in detail by Harald Bohr , generalized to almost periodic functions. Bohl examined these in connection with celestial mechanical problems (perturbation theory). In his dissertation Bohl also investigated differential equations of mechanical systems around their equilibrium points using topological methods (following Henri Poincaré and Adolf Kneser ) and in 1904 proved a form of Brouwer's fixed point theorem for the continuous mapping of the sphere to itself (seven years before the work of Luitzen Egbertus Jan Brouwer from 1911). The set of Poincaré Bohl is named after him here and Henri Poincaré. He also carried out early studies on the uniform distribution of numbers mod 1 in the sense of the later work of Hermann Weyl , also in connection with celestial mechanics.

Bohl was also a strong chess player who competed with the Baltic chess master Karl Behting for Riga against other European chess clubs (such as the one in Berlin). For example, he found a “Riga variant” of the Spanish opening .

Bohl never married.

Fonts

literature

  • Adolf Kneser, Alfred Meder: Piers Bohl to the memory . In: Annual report of the German Mathematicians Association , vol. 33 (1925), pp. 25–32 ( digitized version ).
  • Inese Bula: The Riga German-Baltic astronomer Piers Bohl . In: Journal of Baltic Studies , Vol. 24, 1993, pp. 319-326.

Web links

Individual evidence

  1. ↑ Entry in the baptismal register of Walk parish (Estonian: Valga)
personal data
SURNAME Bohl, Piers
BRIEF DESCRIPTION Livonian mathematician
DATE OF BIRTH October 23, 1865
PLACE OF BIRTH Walk , Livonia Governorate
DATE OF DEATH December 25, 1921
Place of death Riga