Charles de la Vallée Poussin

Charles-Jean de La Vallée Poussin (1866-1962) taught mathematical analysis at the Université catholique de Louvain university for over sixty years. He was also in charge of rational mechanics, mathematical physics and the history of science for shorter periods. His figure undoubtedly dominated mathematics in Belgium during the first half of the twentieth century and his value was recognized worldwide.

de la Vallée Poussin made himself known to the learned world by demonstrating in 1896, along with Hadamard and independently, Gauss's conjecture on the asymptotic distribution of prime numbers, a result known today as the prime number theorem.

A virtuoso of the theory of functions of a complex variable, he was also one of the very first to grasp the importance of the nascent theory of functions of real variables created by Baire, Borel and Lebesgue. He immediately made essential contributions to it, which he included in the first editions of his Course of Infinitesimal Analysis, universally regarded as a model of the genre, and republished a dozen times.

de la Vallée Poussin then devoted himself to approximation theory, quasi-analytical functions, ordinary differential equations, conformal representation, and the theory of potential, areas where his original contributions and monographs are still used today. We know less that one of his articles is truly the foundation of linear programming.

This work is the subject of more than 150 notes and memoirs, and has earned him numerous scientific distinctions. Member of the Académie Royale de Belgique for over sixty years, associate of the Institut de France, and founding member of the Académie Pontificale des Sciences, he chaired the Congrès international des mathématiciens de Strasbourg in 1922, before becoming President of honor of the International Mathematical Union. The King Albert I made him baron in 1928.

It is important for our Alma mater to preserve and maintain the memory of such a scientific personality. On October 8, 1987, the name of Charles de La Vallée Poussin was given to the main audience of the de Hemptinne building. A bust, a portrait and various documents relating to de la Vallée Poussin's career are on permanent display.

A de laVallée Poussin Chair will periodically be entrusted to a leading mathematical personality.

The publication of the scientific works of Charles de La Vallée Poussin was undertaken many years ago by Prof. Jean Mawhin, from UCLouvain, Paul Butzer, from the Technological University of Aix-la-Chapelle, and Pasquale Vetro, from the University of Palermo. The first volume, devoted to biographical aspects and contributions to number theory, was published in 2000. Volume II deals mainly with the theory of measurement and integration and differential equations and volume III with the theory of the approximation. Volume IV devoted to the theory of potential and conformal representation appears in 2017 and closes this major project. All the volumes are co-edited by the Académie Royale de Belgique and the Circolo Matematico di Palermo.