About Henri Lebesgue
Henri Léon Lebesgue was a French mathematician known for his theory of integration, which was a generalization of the 17th-century concept of integration—summing the area between an axis and the curve of a function defined for that axis. His theory was published originally in his dissertation Intégrale, longueur, aire at the University of Nancy during 1902. Lebesgue's first paper was published in 1898 and was titled "Sur l'approximation des fonctions". The first of these, unrelated to his development of Lebesgue integration, dealt with the extension of Baire's theorem to functions of two variables.
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