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Prix Leroy P. Steele 2019

Anaïs Jaunay - Citizen Press (*) - 15/01/2019

Philippe Flajolet, a pioneer of algorithmics, is awarded the Leroy P. Steele Prize

Philippe Flajolet © Inria / Photo C. Tourniaire

Nobody aware of the importance of his work will be surprised to see Philippe Flajolet featuring once again among the biggest names in the world of mathematics, the American Mathematical Society  in particular. More than eight years after his sudden death, Flajolet is to be awarded the Leroy P. Steele Prize for Mathematical Excellence on 17 January 2019. He will share this prize with Robert Sedgewick from Princeton University, with whom he wrote the book Analytic Combinatorics , which was published in 2009.

A student of the École Polytechnique, a Doctor of Science (PhD), passionate about both technical and linguistic problems and remarkably erudite, Philippe Flajolet was a presence at Inria for the best part of forty years. Continuing in the tradition of the most prominent defenders of interdisciplinarity, he made his mark on the field of mathematics through his ground-breaking work in analytic combinatorics.

A global figure in algorithmics

Philippe Flajolet joined the IRIA (now known as Inria) in 1971, becoming a member of the “Formal languages and automation” team headed up by Maurice Nivat, alongside Gérard Huet, Jean-Marc Steyaert and Bruno Courcelle. As a result of a chance encounter with Jean Vuillemin, Flajolet soon made the decision to turn towards algorithmic analysis, with a particular focus on the analysis of private complex networks, the automation of analysis methods, the application of probabilistic algorithms and quantitative research. The original, meticulous work he carried out soon had an influential impact, seeing Philippe Flajolet become a central figure in the world of algorithmics.

Alongside Robert Sedgewick, chairman of the Department of Computer Science at Princeton, he wrote two key volumes: An Introduction to the Analysis of Algorithms in 1996 and Analytic Combinatorics in 2009, for which they have now been recognised.

Recognition for his achievements

Awarded the Grand prix Scienceby the UAP (1986), the Computing Science prize by the Académie des sciences (1994) and the silver medal by the CNRS in 2004; made a member of the Academia Europaea in 1995, and the Académie des sciences in 2003, before becoming a Knight of the Legion of Honour in 2010, the career of this leading figure in the scientific community was littered with awards. Eight years after his death, it is now the turn of the prestigious American Mathematical Society to pay tribute to his landmark work in the field of mathematics, work that helped Inria become significantly more influential at an international level.

The applications of the theory of analytic combinatorics - one of a number of combinatoric techniques used to count objects that uses the internal structure of objects in order to derive formulae for their generating functions, using complex analysis techniques to obtain asymptotic values - are now omnipresent in our everyday lives, from super-fast search engines to communication protocols and formal calculations. With his uncanny knack for describing complicated concepts in a straightforward way, Flajolet spoke of his field as: “A method or a way of putting forward a detailed description of the steps needed to do something: sorting objects, locating towns on a map, multiplying two numbers together, extracting a square root, searching for a word in a dictionary, etc.”

Leroy P. Steele Prize 2019

Philippe Flajolet, who died suddenly in 2011, is to be recognised alongside Robert Sedgewick for their volume Analytic Combinatorics, published in 2009 by Cambridge University. The book’s publication was a major breakthrough for the discipline, with analytic combinatorics becoming a flourishing sub-discipline of mathematics and a key component in algorithmic analysis. The Leroy P. Steele Prize is recognition for the impact and the influence that this volume had, combining analytical and explanatory skills, putting the subject in a historical context and identifying and outlining techniques that had never been previously explored.

Keywords: Philippe Flajolet Heritage History of Computing History of Inria