### Hubert Delange

We learned with sadness of the death on July 25, 2003, in his ninetieth year, of Hubert Delange, professor emeritus at Université de Paris-Sud.

In 1958, Hubert Delange founded the mathematics department at Orsay. In 1982, he retired on the occasion of a congress on analytical number theory, his field of speciality.
After teacher training studies, he defended a thesis on analysis under the direction of Paul Montel. He was imprisoned during the last war and then became a Professor at Université Clermond-Ferrand. He gradually turned to analytical number theory, where the goal is the study of certain entitities, in particular prime numbers, using real and complex analysis.

He was a prolific researcher, meticulous author and was known for his tauberian theorems and results on arithmetic functions.

His enthusiasm for mathematics was life-long and he continued to publish as late as 2000.

With Charles Pisot and subsequently George Poitou, he created at the end of the Fifties, the Paris Number Theory Seminar (called "DPP" by French number theorists), which met on Mondays after midday, at the Institute Henri Poincaré. This seminar played a vital role in the rebirth of the theory of the numbers in France. Many students have fond memories of his availability, of his high standards of rigour and also his kindness. He was a much appreciated colleague and taught in the first cycle through to the third cycle. He had a lively sense of humour.

Hédi Daboussi and Etienne Fouvry

Mathématiques

Orsay

French original