Charles-Jean de La Vallée Poussin

from Wikipedia, the free encyclopedia
Baron Charles-Jean de La Vallée Poussin around 1900

Charles-Jean Gustave Nicolas Baron de La Vallée Poussin [pu'sɛ̃] (born August 14, 1866 in Leuven , † March 2, 1962 in Brussels ) was a Belgian mathematician who is best known for his proof of the prime number theorem.

Life

His father Charles Louis Joseph de La Vallée Poussin (1827-1903) was a geology and mineralogy professor in Leuven, still known today for some classic monographs and the preparatory work for the geological map of Belgium. His great-grandfather, a painter in the 18th century (his son Etienne (1735-1802) was a well-known French history painter), added Poussin to the family name Lavallée when he married a descendant of the painter Nicolas Poussin . Vallée-Poussin first studied at the Jesuit College (College Saint-Stanislas) in Mons with the aim of entering the order himself, but then switched to studying mining, which he graduated with an engineering degree in 1890. He also studied mathematics in Leuven with Louis-Philippe Gilbert, where he received his doctorate in 1890. In 1891 he became an assistant in Leuven (in that year he held his first analysis lecture), where he became a professor a year after the death of Gilbert. In 1892/3 he attended the lectures of Camille Jordan , Henri Poincaré and Charles Émile Picard in Paris and from 1893–1894 the lectures of Hermann Amandus Schwarz , Ferdinand Georg Frobenius and Lazarus Immanuel Fuchs in Berlin .

He began working on differential equations , but quickly became famous in 1896 with the proof of the prime number theorem of analytic number theory , at the same time as Jacques Hadamard . In 1899 he showed that the integral logarithm is an even better approximation to the prime number distribution and derived an asymptotic error term for this approximation. Vallée-Poussin married in 1900. During the First World War, which wreaked havoc in Löwen (fire in the library, shooting of civilians by the German occupation) and where the draft of the 2nd volume of the 3rd edition of his analysis textbook also fell victim, was he partly at Harvard University (1915), Paris ( Collège de France and Sorbonne , 1916, 1917 and 1918) and Geneva (1917-1918). According to the prime number theorem, in 1916 he provided a tightening of the proof by Godfrey Harold Hardy (1914) that an infinite number of zeros of the Riemann zeta function lie on the critical line (real part 1/2). But then he devoted himself to a. Questions about the approximation of functions using trigonometric functions and polynomials and from the 1920s problems of function theory (conformal representations) and potential theory . Vallée Poussin was also one of the first to recognize the importance of the work of Rene Baire , Henri Lebesgue and Émile Borel in real analysis and measurement theory and to take it up in his lectures and books. Like Hadamard, he reached a great age and died of a broken shoulder.

With a work from 1911 ( Sur la methode de l'approximation minimum , Annales de la societe scientifique de Bruxelles, vol. 35 B., pp. 1–16), Vallee-Poussin is also counted among the pioneers of linear optimization .

He showed that a Fourier series which converges to a finite Lebesgue integrable function f (x) except for places in a countable set is the Fourier series of this function f (x).

He is also known for his Cours d'Analyse, his two-volume analysis textbook, which was first published in 1903 and 1906, respectively.

De La Vallée-Poussin had been a member of the Belgian Academy of Sciences since 1909. He was also a member of a number of foreign academies (Paris, Madrid, Naples, the Institut de France , the Pontifical Academy , Accademia dei Lincei in Rome, American National Academy of Sciences , American Academy of Arts and Sciences (1915)). He was the commander of the Legion of Honor in France. In 1930 he was ennobled by the Belgian king with the title of baron. In 1920 he was the first president (honorary president) of the International Mathematical Union and in 1922 (in times of mutual animosity among former war opponents) he was president of the International Congress of Mathematicians in Strasbourg, where he also gave one of the plenary lectures (Sur les fonctions à variation bornée et les questions qui s 'y rattachent).

One of his students is the cosmologist Georges Lemaître (license thesis in mathematics 1920). A guest professor position was established at the Catholic University of Leuven with the Chaire de La Vallée Poussin .

Fonts

literature

  • Burkill in Dictionary of Scientific Biography and Journal London Mathematical Society Vol. 39, 1964, p. 165
  • Paul Montel, obituary in Compte Rendue Acad. Sciences Paris Vol. 254, 1962, p. 2473
  • Jean Mawhin: The Cours d'Analyse Infinitésimale of Charles-Jean de La Vallée Poussin: From Innovation to Tradition, Annual Report DMV, Volume 116, Issue 4, 2014, pp. 243-259.

Web links

Individual evidence

  1. ↑ z. B. George Dantzig Linear Programming , Operations Research, Vol. 50, 2002, Tikhomirov The Evolution of convex Optimization in American Mathematical Monthly January 1996.
personal data
SURNAME De la Vallée Poussin, Charles-Jean
ALTERNATIVE NAMES De La Vallée Poussin, Charles-Jean Gustave Nicolas Baron (full name)
BRIEF DESCRIPTION Belgian mathematician
DATE OF BIRTH August 14, 1866
PLACE OF BIRTH Lions
DATE OF DEATH March 2, 1962
Place of death Brussels