Grasse 1928 - Paris 2001


Brief scientific biography

Jacques Louis Lions was born in Grasse, in the district of Alpes-Maritimes, in south-eastern France, on May 3, 1928. There he attended primary and secondary school. In 1943, at the young age of 15, he joined the Forces Françaises de l'Intérieur, the Resistance against the German occupation. In 1946 he left his beloved hometown to study at the Lycée Félix-Faure of Nice, and in 1947 he entered the école Normale Supérieure of Paris. He obtained the doctorate in 1954 at the University of Nancy, where he had studied with a grant from the Centre National de la Recherche Scientifique. His dissertation, entitled "Problèmes aux limites en théorie des distributions", prepared under the supervision of Fields Medallist Laurent Schwartz, was published in Acta Mathematica. In the same year he was appointed professor. He remained in Nancy until 1962; then he moved to Paris, where he taught numerical analysis at the Faculty of Science of the University of Paris (later, at the Université Paris VI "Pierre et Marie Curie") until 1973. There he initiated a weekly seminar at the Institut Blaise Pascal, and set up a laboratory that now bears his name. At the same time, he was a part-time professor at the école Polytechnique from 1966 to 1986, and was then appointed honorary professor. In 1973 he was named by the Collège de France to the Chair of "Mathematical Analysis of Systems and their Control", which he retained until his retirement in 1998. In 1973 he was also elected to the Académie des Sciences, where he was to become vice-president in 1995 and then president in the term 1996-1998. He held high-level managing and counselling positions in several scientific organizations, governmental institutions and industrial companies, among which: the Institut National de Recherche en Informatique et en Automatique (INRIA) (1980-1984), of which he was the founder, the Ministére de l'Industrie et de la Recherche (1983-1984), the Centre National d'études Spatiales (1984-1992), the Conseil Scientifique d'électricité de France (1986-1996), the Comité Scientifique de la Météorologie Nationale (1990-2001), the Conseil Scientifique de Gaz de France (1993), and the Conseil Scientifique de France Télécom (1998-2001).
He was President of the International Mathematical Union from 1991 to 1994, and in this capacity he proclaimed the year 2000 as the World Mathematical Year. This year is also memorable for the moment when, during an official ceremony at the Elysée Palace, with the members of the Académie des Sciences as invited guests, Lions handed to President Chirac, as the result of a three-year teamwork, a detailed report on the most recent scientific achievements concerning the following socially relevant issues: "access to knowledge for all and electronic processing of information; knowledge of our planet and ways of life; and understanding life systems and improving healthy care of all."
The most remarkable feature of his scientific profile is, indeed, the steady effort towards theoretical progress combined with a great interest in applications in economics, technology and environmental sciences. Following the original approach of Laurent Schwartz, based on distributions, he succeeded in enhancing the theory of partial differential equations in a ground-breaking way, not only improving its understanding in the framework of variational calculus, but also investigating its connections with interdisciplinary topics such as optimizations problems, fluid dynamics, system control and material physics. Working in this direction, he strongly endorsed the use of computer-based numerical techniques and the implementation of symbolic algorithms. He authored over 400 scientific papers and 20 expository books, among which the nine volumes of the monumental treatise "Analyse Mathématique et Calcul Numérique pour les Sciences et les Techniques" (1984-1985), written with Robert Dautray, which is often referred to as his masterpiece and lifework.
Lions is nowadays regarded as the father of applied mathematics in France. At a time when, in his country, the structural approach of the Bourbaki group was the predominant trend, he had the far-sightedness and courage to move against the tide, and search for interactions with the real world.
Lions collected a huge number of prestigious international awards. Degrees honoris causa were bestowed on him by nineteen universities throughout the world. Moreover, he won the Grand Prix Cognacq-Jay of the Académie des Sciences (1972), the John Von Neumann Prize (1986), the Japan Prize in Applied Mathematics (1991), the Harvey Prize of Technion, Ha´fa, Israel (1991), the Daedalon Gold Medal for Science and Technology of Greece (1991), the W.T. and Idalia Reid Prize of the Society for Industrial and Applied Mathematics (1998), the Prix Lagrange of International Conferences in Industrial and Applied Mathematics (1999), and the Hilbert Medal of the International Society for Computational Engineering & Sciences (2000).
He also received the following decorations: Commandeur de la Légion d'Honneur (1993), Grand Officier dans l'Ordre National du Mérite (1998), from France, and the Order of the Rising Sun, Gold and Silver Star (1998) from Japan.
As a result of the international spread of his research activity, he became member of over twenty foreign academies. His innumerable scientific visits abroad left a lasting mark, especially in developing countries; he played a major role in the creation of an "applied" branch of the Tata Institute in Bangalore (India), and in the foundation of the Laboratoire franco-chinois d'Informatique, d'Automatique et de Mathématiques Appliquées in Beijing, and of the Institut Sino-Français de Mathématiques Appliquées in Shangai, and thoroughly supported the Third World Academy of Sciences in the promotion of mathematical research in Africa.

His Commitment to Education

Lions's versatile, far-reaching gifts and his intensive engagement in the innovation process of mathematics earned him not only worldwide fame, but also the devoted admiration of his colleagues and his students (at least 40, with a total of over 1,000 descendants, spread over six scientific generations). Enrico Magenes, with whom Lions coauthored a three-volume book on nonhomogeneous boundary value problems between 1968 and 1970, says:
"I had the opportunity to fully appreciate the intellectual and human qualities of Lions: his unaffected manners; his commitment and energy in work; his rapidity of intuition and decision; his openness to new ideas and new problems in a body of knowledge that increased more and more over time, even outside mathematics; his love of freedom; and his respect for the opinions of others."
According to Peter D. Lax,
"Lions had an open, friendly, generous personality, with a light touch and a subtle sense of humour."
And these are the words of gratitude expressed by his student Roger M. Temam in his commemorative article:
"All his students were delighted and amazed at how quickly he would read their drafts and how available he would be to each of them individually. Another reason for his success as thesis and postdoctoral advisor is that he could determine very quickly what research would suit a new student, and he would tailor new problems adapted to the student's abilities. [...] He was very careful not to influence his students too much, saying that he saw himself as a counsellor, trying only to help his students develop the best of their possibilities. [...] Jacques-Louis Lions was an exceptional person in many respects. He was a charismatic man, generous, very open and accessible, avoiding conflicts and contentious situations. One of the most striking aspects of his personality was his long-term vision; he was able to see and get involved in things that came to maturity five, ten, or twenty years later. He had many good ideas, and he had the mathematical talent, the physical strength, and the understanding of people needed to implement them. "
Philippe G. Ciarlet recalls that
"He never complained, reserving his sympathy for others. His deep intelligence, his communicative vision and his warm friendship have marked all who came in contact with him."
These personal memories, together with the extraordinary talent he passed on to his son Pierre-Louis (who won the Fields Medal in 1994), are Jacques-Louis Lions's invaluable human legacy.
Jacques-Louis Lions died in Paris on May 17, 2001.

Essential bibliography

P. BERNHARD 2002, Jacques Louis Lions, Automatica, April.
PH.G. CIARLET, Jacques-Louis Lions (1928-2001) , Laboratoire Jacques-Louis Lions (UMR 7598), Paris. http://www.ann.jussieu.fr/jllions/Ciarlet_Lions.ps
A. DAHAN-DALMEDICO 2005, Jacques-Louis Lions, un mathématicien d'exception entre recherche, industrie et politique, La Découverte, coll. Histoire des Sciences/Textes, Paris.
P.D. LAX, E. MAGENES, R. TEMAM 2001, Jacques-Louis Lions (1928-2001) , Notices of the American Mathematical Society, December
E. MAGENES 2001, Ricordo di Jacques Louis Lions, Notiziario dell'Unione Matematica Italiana, June. http://acm.smai.emath.fr/congres-jllions/magenes.html
J. MAWHIN 2001, Jacques-Louis Lions (1928-2001) , Académie Royale de Belgique, Bulletin de la Classe de Sciences.
R.M. TEMAM 2001, Jacques-Louis Lions, SIAM News, July.
J-CHR. YOCCOZ, Jacques-Louis Lions (1928-2001) , Collège de France.
(English version: European Mathematical Society Newsletter, December 2001)

Margherita Barile
Università di Bari