Valiant Receives 2010 Turing Award

The Association for Computing Machinery (ACM) enumeration problems can be has announced that Leslie G. Valiant of Harvard intractable even when the cor- University is the recipient of the 2010 A. M. Tur- responding decision problem is ing Award “for transformative contributions to tractable. Another fundamental the theory of computation, including the theory contribution to computational of probably approximately correct (PAC) learning, complexity was Valiant’s theory the complexity of enumeration and of algebraic of algebraic computation, in computation, and the theory of parallel and distrib- which he established a frame- uted computing.” The award carries a cash prize work for understanding which of US$250,000 and will be presented to Valiant at algebraic formulas can be evalu- the annual ACM Awards Banquet on June 4, 2011, ated efficiently. In analogy with in San Jose, California. the Boolean complexity classes P and NP, his theory character- Citation izes the difficulty of computing Over the past thirty years, Leslie Valiant has made fundamental functions in linear Leslie G. Valiant fundamental contributions to many aspects of algebra, namely the determinant theoretical computer science. His work has opened and permanent. Together with new frontiers, introduced ingenious new concepts, his work on #P, this set the stage for some of the and presented results of great originality, depth, most exciting subsequent developments in com- putational complexity, such as the development of and beauty. Time and again, Valiant’s work has interactive proofs for problems beyond NP. literally defined or transformed the computer sci- A third broad area in which Valiant has made ence research landscape. important contributions is the theory of parallel Valiant’s greatest single contribution may be and distributed computing. His design of random- his 1984 paper “A Theory of the Learnable”, which ized routing strategies laid the groundwork for a laid the foundations of computational learning rich body of research that exposed how random- theory. He introduced a general framework as well ization can be used to offset congestion effects in as concrete computational models for studying the communication networks. He proposed the bulk learning process, including the famous “probably synchronous model of parallel computation. He approximately correct” (PAC) model of machine also posed a number of influential challenges lead- learning. This has developed into a vibrant research ing to the construction of parallel algorithms for area and has had enormous influence on machine seemingly inherently sequential problems. Finally, learning, artificial intelligence, and many areas the superconcentrators constructed by Valiant in of computing practice, such as natural language the context of computational complexity estab- processing, handwriting recognition, and com- lished the fundamental role of expander graphs puter vision. in computation. Valiant has made many seminal contributions to computational complexity. He introduced the notion of complexity of enumeration, in terms Biographical Sketch of the complexity class #P. The most surpris- Leslie Valiant received his Ph.D. in computer ing consequence of this study was that natural science from the University of Warwick in 1974.

JUNE/JULY 2011 NOTICES OF THE AMS 833 He taught at Carnegie Mellon University, Leeds University, and the University of Edinburgh and is currently the T. Jefferson Coolidge Professor of Computer Science and Applied Mathematics at Harvard University’s School of Engineering and Applied Sciences (SEAS). He is the recipient of the 1986 Nevanlinna Prize from the International Mathematical Union, the 1997 Knuth Prize from the ACM Special Interest Group on Algorithms and Computation Theory (SIGACT) and the IEEE Techni- cal Committee on the Mathematical Foundations of Computing, and the 2008 European Association for Theoretical Computer Science (EATCS) Award. He is a Fellow of the Royal Society (London), a Fellow of the American Association for Artificial Intelli- gence, and a member of the National Academy of Sciences of the USA. His research interests include complexity theory, computational learning, and parallel computation, as well as computational neuroscience, evolution, and artificial intelligence.

About the Award The A. M. Turing Award was named for Alan M. Turing, the British mathematician who articulated the mathematical foundation and limits of comput- ing and who was a key contributor to the Allied cryptanalysis of the German Enigma cipher during World War II. Since its inception in 1966 the Turing Award has honored the computer scientists and engineers who created the systems and underlying theoretical foundations that have propelled the information technology industry. The award is given to an individual selected for contributions of a technical nature made to the com- puting community. The contributions should be of lasting and major technical importance to the com- puter field. Financial support for the Turing Award is provided by the Intel Corporation and Google Inc.

— ACM announcement

834 NOTICES OF THE AMS VOLUME 58, NUMBER 6