Leslie Valiant

Leslie Valiant
Leslie Valiant in 2005 (photo from MFO)
Born	Leslie Gabriel Valiant (1949-03-28) 28 March 1949 Budapest, Hungarian Republic
Nationality	United Kingdom
Fields	Mathematics Computer Science
Institutions	Harvard University University of Edinburgh
Alma mater	University of Cambridge Imperial College London University of Warwick
Thesis	Decision Procedures for Families of Deterministic Pushdown Automata (1974)
Doctoral advisor	Mike Paterson
Doctoral students	Mark Jerrum Michael Kearns Dan Roth Rocco Servedio
Known for	Valiant–Vazirani theorem Counting problem (complexity)
Notable awards	ACM Turing Award (2010) EATCS Award (2008) Knuth Prize (1997) AAAI Fellow (1992) FRS (1991) Nevanlinna Prize (1986)

Leslie Gabriel Valiant FRS (born 28 March 1949) is a British computer scientist and computational theorist. He is currently the T. Jefferson Coolidge Professor of Computer Science and Applied Mathematics at Harvard University.

Education

Valiant was educated at King's College, Cambridge, Imperial College London, and University of Warwick where he received a PhD in computer science in 1974.

Research

Valiant is world-renowned for his work in theoretical computer science. Among his many contributions to complexity theory, he introduced the notion of #P-completeness to explain why enumeration and reliability problems are intractable. He also introduced the "probably approximately correct" (PAC) model of machine learning that has helped the field of computational learning theory grow, and the concept of holographic algorithms. His earlier work in automata theory includes an algorithm for context-free parsing, which is (as of 2010) still the asymptotically fastest known. He also works in computational neuroscience focusing on understanding memory and learning.

Valiant's 2013 book is Probably Approximately Correct: Nature's Algorithms for Learning and Prospering in a Complex World (Basic Books, ISBN 9780465032716). In it he argues, among other things, that evolutionary biology cannot explain the rate at which evolution occurs, writing, for example, "The evidence for Darwin's general schema for evolution being essentially correct is convincing to the great majority of biologists. This author has been to enough natural history museums to be convinced himself. All this, however, does not mean the current theory of evolution is adequately explanatory. At present the theory of evolution can offer no account of the rate at which evolution progresses to develop complex mechanisms or to maintain them in changing environments."

Career

Valiant started teaching at Harvard University in 1982 and is currently the T. Jefferson Coolidge Professor of Computer Science and Applied Mathematics in the Harvard School of Engineering and Applied Sciences. Prior to 1982 he taught at Carnegie Mellon University, the University of Leeds, and the University of Edinburgh.

Books

Valiant, Lesslie (2013). Probably Approximately Correct

Valiant, Lesslie (2000). Circuits of the Mind

Awards and honors

Valiant received the Nevanlinna Prize in 1986, the Knuth Prize in 1997, the EATCS Award in 2008, and the ACM Turing Award in 2010. He is a Fellow of the Royal Society (London), a Fellow of the American Association for Artificial Intelligence, and a member of the National Academy of Sciences (USA).

Valiant's nomination for the Royal Society reads:

1. REDIRECT Template:Cquote

• This is a redirect from a page that has been moved (renamed). This page was kept as a redirect to avoid breaking links, both internal and external, that may have been made to the old page name. For more information follow the bold category link.

Family

His two sons Gregory Valiant and Paul Valiant are both theoretical computer scientists, as faculty at Stanford and Brown University respectively.

References

Template:Nevanlinna Prize winners