Alain Chenciner (born 23 October 1943, in

Villeneuve-sur-Lot Villeneuve-sur-Lot (; in the Languedocien dialect of Occitan language: ''Vilanuèva d'Òlt'' ) is a town and commune in the southwestern French department of Lot-et-Garonne. The commune was formerly named ''Villeneuve-d'Agen''. Villeneuve-sur-L ...

) is a French mathematician, specializing in

dynamical system In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, the flow of water in ...

s with applications to

celestial mechanics Celestial mechanics is the branch of astronomy that deals with the motions of objects in outer space. Historically, celestial mechanics applies principles of physics (classical mechanics) to astronomical objects, such as stars and planets, to ...

Chenciner studied from 1963 to 1965 at the

École polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

and did research from 1966 for CNRS (Attachée de Recherche) at the École Polytechnique (at the Centre de Mathématiques founded by

Laurent Schwartz Laurent-Moïse Schwartz (; 5 March 1915 – 4 July 2002) was a French mathematician. He pioneered the theory of distributions, which gives a well-defined meaning to objects such as the Dirac delta function. He was awarded the Fields Medal in ...

). In 1971 he received his Ph.D. from the

University of Paris XI Paris-Sud University (French: ''Université Paris-Sud''), also known as University of Paris — XI (or as Université d'Orsay before 1971), was a French research university distributed among several campuses in the southern suburbs of Paris, in ...

under Jean Cerf with thesis ''Sur la géométrie des strates de petites codimensions de l'espace des fonctions différentiables réelles sur une variété'' (Chenciner's thesis defense involved Henri Cartan,

and René Thom). Chenciner became a ''

maître de conférences ''Maître'' (spelled ''Maitre'' according to post-1990 spelling rules) is a commonly used honorific for lawyers, judicial officers and notaries in France, Belgium, Switzerland and French-speaking parts of Canada. It is often written in its abbrev ...

'' at the University of Paris XI, then in 1973 at the

University of Paris VII A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, t ...

, and in 1975 at the

University of Nice A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, th ...

. He returned in 1978 as ''maître de conférences'' to the University of Paris VII, where in 1981 he became professor extraordinarius (''professeur de première classe'') and in 1991 professor ordinarius (''professeur en classe exceptionelle''). In 2012 he became professor emeritus. At the beginning of his career Chenciner worked on differential topology and its applications to dynamical systems, following the pioneering efforts of Stephen Smale, and also worked on

singularity theory In mathematics, singularity theory studies spaces that are almost manifolds, but not quite. A string can serve as an example of a one-dimensional manifold, if one neglects its thickness. A singularity can be made by balling it up, dropping it ...

. Later in his career he worked on mathematical problems of celestial mechanics (specifically, the

three-body problem In physics and classical mechanics, the three-body problem is the problem of taking the initial positions and velocities (or momenta) of three point masses and solving for their subsequent motion according to Newton's laws of motion and Newton's ...

and the

n-body problem In physics, the -body problem is the problem of predicting the individual motions of a group of celestial objects interacting with each other gravitationally.Leimanis and Minorsky: Our interest is with Leimanis, who first discusses some histor ...

) and studied bifurcations at elliptical fixed points of dynamical systems. Chenciner, with Jacques Laskar, founded in 1992 the research group ''astronomie et systèmes dynamiques'' at the

Observatory of Paris The Paris Observatory (french: Observatoire de Paris ), a research institution of the Paris Sciences et Lettres University, is the foremost astronomical observatory of France, and one of the largest astronomical centers in the world. Its histor ...

. In 2002 he was an

invited speaker at the International Congress of Mathematicians This is a list of International Congresses of Mathematicians Plenary and Invited Speakers. Being invited to talk at an International Congress of Mathematicians has been called "the equivalent, in this community, of an induction to a hall of fame." ...

in Beijing and gave a talk ''Action minimizing solutions of the Newtonian n-body problem: from homology to symmetry''. He became in 2012 a fellow of the

American Mathematical Society The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, ...

. He gave a eulogy on 9 July 2012 at cimetière du Montparnasse to mark the centenary of the death of Henri Poincaré. Chenciner's doctoral students include Daniel Bennequin.

Selected publications

*as editor with Richard Cushman, Clark Robinson, and Zhihong Jeff Xia: Celestial Mechanics, dedicated to Donald Saari for his 60th birthday, Contemporary Mathematics, American Mathematical Society 2002 *Courbes Algébriques Planes, Springer Verlag 2007
Three Body Problem, Scholarpedia

References

External links

Alain Chenciner's Homepage
{{DEFAULTSORT:Chenciner, Alain 1943 births Living people 20th-century French mathematicians 21st-century French mathematicians University of Paris alumni Academic staff of the University of Paris École Normale Supérieure alumni Fellows of the American Mathematical Society People from Villeneuve-sur-Lot