Passage: His parents were Jacques-Louis Lions, a mathematician and at that time professor at the University of Nancy, who became President of the International Mathematical Union, and Andrée Olivier, his wife. He graduated from the École normale supérieure  in 1977 (same year as Jean-Christophe Yoccoz, another Fields Medalist). Refusing to take the agrégation in Mathematics, he chose to carry out research in applied mathematics and received his doctorate from the University of Pierre and Marie Curie in 1979.Lions received the Fields Medal, for his work on theory of nonlinear partial differential equations, in 1994 while working at the University of Paris-Dauphine. He was the first to give a complete solution to the Boltzmann equation with proof. Other awards Lions received include the IBM Prize in 1987 and the Philip Morris Prize in 1991. He was an invited professor at the Conservatoire national des arts et métiers (2000). He is a doctor honoris causa of Heriot-Watt University (Edinburgh), Narvik University College (2014), and of the City University of Hong-Kong and is listed as an ISI highly cited researcher. He holds the position of Professor of Partial differential equations and their applications at the Collège de France in Paris as well as a position at École Polytechnique.

Question: What position do the Professor hold?
Professor of Partial differential equations and their applications