Lebesgue, Henri (Léon)[luhbeg](1875--1941) Mathematician, born in Beauvais, N France. He studied at the Ecole Normale Supérieure, and taught at Rennes, Poitiers, the Sorbonne, and the Collège de France. Following the work of Emile Borel and René Baire (1874--1932), he developed the theory of measure and integration which bears his name, and applied it to many problems of analysis, in particular to the theory of Fourier series. |