Tony Hoare

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Sir Tony Hoare
Sir Tony Hoare IMG 5125.jpg
Sir Charles Antony Richard Hoare giving a conference at EPFL on 20 June 2011
Born Charles Antony Richard Hoare
(1934-01-11) 11 January 1934 (age 88)
Colombo, British Ceylon
Residence Cambridge
Fields Computer science
Alma mater
Doctoral students
Known for
Notable awards

Sir Charles Antony Richard Hoare FRS FREng[3] (born 11 January 1934),[4] commonly known as Tony Hoare or C. A. R. Hoare, is a British computer scientist. He developed the sorting algorithm quicksort in 1959/1960.[5] He also developed Hoare logic for verifying program correctness, and the formal language Communicating Sequential Processes (CSP) to specify the interactions of concurrent processes (including the dining philosophers problem) and the inspiration for the occam programming language.[6][7][8][9][10]


Born in Colombo, Ceylon (now Sri Lanka) to British parents, Tony Hoare's father was a colonial civil servant and his mother was the daughter of a tea planter. Hoare was educated in England at the Dragon School in Oxford and the King's School in Canterbury.[11] He then studied Classics and Philosophy ("Greats") at Merton College, Oxford. On graduating in 1956 he did 18 months National Service in the Royal Navy, where he learned Russian.[12] He returned to Oxford University in 1958 to study for a postgraduate certificate in Statistics, and it was here that he began computer programming, having been taught Autocode on the Ferranti Mercury by Leslie Fox.[13] He then went to Moscow State University as a British Council exchange student, where he studied machine translation under Andrey Kolmogorov.[12]

In 1960, he left the Soviet Union and began working at Elliott Brothers, Ltd, a small computer manufacturing firm, where he implemented ALGOL 60 and began developing major algorithms.[14][15] He became the Professor of Computing Science at the Queen's University of Belfast in 1968, and in 1977 returned to Oxford as the Professor of Computing to lead the Programming Research Group in the Oxford University Computing Laboratory (now Department of Computer Science, University of Oxford), following the death of Christopher Strachey. He is now an Emeritus Professor there, and is also a principal researcher at Microsoft Research in Cambridge, England.

Hoare's most significant work has been in the following areas: his sorting and selection algorithm (Quicksort and Quickselect), Hoare logic, the formal language Communicating Sequential Processes (CSP) used to specify the interactions between concurrent processes, structuring computer operating systems using the monitor concept, and the axiomatic specification of programming languages.[16][17]

In 1982, he was elected a Fellow of the Royal Society.[18] He was elected in 2005 as a Fellow[3] of the Royal Academy of Engineering[3]

Apologies and retractions

Speaking at a conference in 2009, he apologised for inventing the null reference:[19]

I call it my billion-dollar mistake. It was the invention of the null reference in 1965. At that time, I was designing the first comprehensive type system for references in an object oriented language (ALGOL W). My goal was to ensure that all use of references should be absolutely safe, with checking performed automatically by the compiler. But I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years.

For many years under his leadership his Oxford department worked on formal specification languages such as CSP and Z. These did not achieve the expected take-up by industry, and in 1995 Hoare was led to reflect upon the original assumptions:[20]

Ten years ago, researchers into formal methods (and I was the most mistaken among them) predicted that the programming world would embrace with gratitude every assistance promised by formalisation to solve the problems of reliability that arise when programs get large and more safety-critical. Programs have now got very large and very critical – well beyond the scale which can be comfortably tackled by formal methods. There have been many problems and failures, but these have nearly always been attributable to inadequate analysis of requirements or inadequate management control. It has turned out that the world just does not suffer significantly from the kind of problem that our research was originally intended to solve.




  1. Tony Hoare at the Mathematics Genealogy Project
  2. Sir Antony Hoare 2006 Fellow
  3. 3.0 3.1 3.2 3.3 3.4 3.5 "List of Fellows".<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  4. "Birthdays Jan 10". The Times. London. 10 January 2009. Retrieved 9 January 2010.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  5. In 1959, while studying machine translation of languages in Moscow, he invented the now well-known sorting algorithm, "Quicksort."
  6. Tony Hoare from the Association for Computing Machinery (ACM) Digital Library
  7. Tony Hoare's publications indexed by the DBLP Bibliography Server at the University of Trier
  8. List of publications from Microsoft Academic Search
  9. Shustek, L. (2009). "Interview: An interview with C.A.R. Hoare". Comm. ACM. 52 (3): 38–41. doi:10.1145/1467247.1467261.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  10. Hoare, C. A. R. (1974). "Monitors: An operating system structuring concept". Communications of the ACM. 17 (10): 549. doi:10.1145/355620.361161.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  11. Lean, Thomas (2011–12). "Professor Sir Tony Hoare" (PDF). National Life Stories: An Oral History of British Science. UK: British Library. Retrieved 15 September 2014. Check date values in: |date= (help)<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  12. 12.0 12.1 Tony Hoare (Autumn 2009). "My Early Days at Elliotts". Resurrection. Computer Conservation Society (48). ISSN 0958-7403. Retrieved 27 May 2014.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  13. Bill Roscoe; Cliff Jones (2010). "1 Insight, inspiration and collaboration". Reflections on the Work of C.A.R. Hoare (PDF). Springer. ISBN 978-1-84882-911-4.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  14. 14.0 14.1 C.A.R. Hoare (February 1981). "The emperor's old clothes" (PDF). Communications of the ACM. 24 (2): 5–83. doi:10.1145/358549.358561. ISSN 0001-0782.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  15. Hoare, C. A. R. (1981). "The emperor's old clothes". Communications of the ACM. 24 (2): 75. doi:10.1145/358549.358561.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  16. Preface to the ACM Turing Award lecture.
  17. ACM Turing Award citation.
  18. "Fellows". Royal Society. Retrieved 20 November 2010.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  19. Hoare, Tony (25 August 2009). "Null References: The Billion Dollar Mistake".<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  20. Hoare, C. A. R. (1996). "Unification of Theories: A Challenge for Computing Science". Selected papers from the 11th Workshop on Specification of Abstract Data Types Joint with the 8th COMPASS Workshop on Recent Trends in Data Type Specification. Springer-Verlag. pp. 49–57. ISBN 3-540-61629-2.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  21. Hoare, Charles Anthony Richard (27 October 1980). "The Emperor's Old Clothes / The 1980 ACM Turing Award Lecture". Association for Computing Machinery. Archived from the original (PDF) on 3 February 2012.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  22. "Honorary Graduates 1989 to present". University of Bath. Retrieved 18 February 2012.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  23. (Charles) Antony Richard (Tony) Hoare Biography
  24. CHM. "Sir Antony Hoare— CHM Fellow Award Winner". Retrieved 30 March 2015.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>[1]
  25. "Programming Languages Achievement Award 2011". ACM. Retrieved 28 August 2012.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  26. "IEEE John von Neumann Medal Recipients" (PDF). IEEE. Retrieved 26 February 2011.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  27. Diks, Krzysztof (15 November 2012). "Profesor Hoare doktorem honoris causa Uniwersytetu Warszawskiego" (in Polish). University of Warsaw. Retrieved 26 November 2012.CS1 maint: unrecognized language (link)<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  28. "Los informáticos Tony Hoare y Mateo Valero serán investidos hoy doctores honoris causa por la Complutense" (in Spanish). 10 May 2013. Retrieved 10 May 2013.CS1 maint: unrecognized language (link)<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>

Further reading

External links