French mathematician.
His contributions include work in harmonic analysis and differential equations. His integral was the first to be able to integrate all derivatives. Among his students is Gustave Choquet. He is also known for the more general broad Denjoy integral, or Khinchin integral.
Denjoy was not a man lacking interests outside mathematics: on the contrary he was fascinated by topics such as philosophy, psychology, and social studies. He approached such topics from his position as an atheist and an active participant in socialist politics. In particular he was an active member of the Radical Party which was headed by Edouard Herriot. Although Denjoy did not aspire to the political career of Herriot, who served in nine different cabinets and was premier of France three times, Denjoy’s involvement with the Radical Party led to him serving as a town councillor for Montpellier in 1912, and as county councillor for Gers from 1920. He served in this capacity for twenty years.
For his outstanding contributions to the theory of functions of a real variable, Denjoy received many honours. As well as election to the Académie des Sciences in 1941, he was also elected to the academies in Amsterdam, Warsaw, and Liege. He was also honoured by being elected as vice-president of the International Mathematical Union in 1954.
Denjoy died in Paris on 21 January 1974.

Link to Wikipedia biography