Sir Charles Antony Richard Hoare (Tony Hoare or C. A. R. Hoare) (born 11 January 1934) is a British

computer scientist A computer scientist is a person who is trained in the academic study of computer science. Computer scientists typically work on the theoretical side of computation, as opposed to the hardware side on which computer engineers mainly focus ( ...

who has made foundational contributions to

programming languages A programming language is a system of notation for writing computer program, computer programs. Most programming languages are text-based formal languages, but they may also be visual programming language, graphical. They are a kind of computer ...

algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

formal verification In the context of hardware and software systems, formal verification is the act of proving or disproving the correctness of intended algorithms underlying a system with respect to a certain formal specification or property, using formal met ...

, and

concurrent computing Concurrent computing is a form of computing in which several computations are executed '' concurrently''—during overlapping time periods—instead of ''sequentially—''with one completing before the next starts. This is a property of a sys ...

. His work earned him the

Turing Award The ACM A. M. Turing Award is an annual prize given by the Association for Computing Machinery (ACM) for contributions of lasting and major technical importance to computer science. It is generally recognized as the highest distinction in compu ...

, usually regarded as the highest distinction in computer science, in 1980. Hoare developed the

sorting algorithm In computer science, a sorting algorithm is an algorithm that puts elements of a list into an order. The most frequently used orders are numerical order and lexicographical order, and either ascending or descending. Efficient sorting is importan ...

quicksort Quicksort is an efficient, general-purpose sorting algorithm. Quicksort was developed by British computer scientist Tony Hoare in 1959 and published in 1961, it is still a commonly used algorithm for sorting. Overall, it is slightly faster than ...

in 1959–1960. He developed

Hoare logic Hoare logic (also known as Floyd–Hoare logic or Hoare rules) is a formal system with a set of logical rules for reasoning rigorously about the correctness of computer programs. It was proposed in 1969 by the British computer scientist and lo ...

, an

axiomatic An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...

basis for verifying

program correctness In theoretical computer science, an algorithm is correct with respect to a specification if it behaves as specified. Best explored is ''functional'' correctness, which refers to the input-output behavior of the algorithm (i.e., for each input it ...

. In the semantics of

concurrency Concurrent means happening at the same time. Concurrency, concurrent, or concurrence may refer to: Law * Concurrence, in jurisprudence, the need to prove both ''actus reus'' and ''mens rea'' * Concurring opinion (also called a "concurrence"), a ...

, he introduced the formal language communicating sequential processes (CSP) to specify the interactions of concurrent processes, and along with Edsger Dijkstra, formulated the dining philosophers problem. He is also credited with development (and later criticism) of the

null pointer In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown lengt ...

, having introduced it in the

ALGOL ALGOL (; short for "Algorithmic Language") is a family of imperative computer programming languages originally developed in 1958. ALGOL heavily influenced many other languages and was the standard method for algorithm description used by th ...

family of languages. Since 1977, he has held positions at the

University of Oxford The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the world's second-oldest university in contin ...

and Microsoft Research in

Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge beca ...

Education and early life

Tony Hoare was born in

Colombo Colombo ( ; si, කොළඹ, translit=Koḷam̆ba, ; ta, கொழும்பு, translit=Koḻumpu, ) is the executive and judicial capital and largest city of Sri Lanka by population. According to the Brookings Institution, Colombo me ...

, Ceylon (now

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

) to British parents; his father was a colonial

civil servant The civil service is a collective term for a sector of government composed mainly of career civil servants hired on professional merit rather than appointed or elected, whose institutional tenure typically survives transitions of political leaders ...

and his mother was the daughter of a tea planter. Hoare was educated in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

at the

Dragon School ("Reach for the Sun") , established = 1877 , closed = , type = Preparatory day and boarding school and Pre-Prep school , religion = Church of England , president = , head_label = Head , head = Emma Goldsm ...

Oxford Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the Un ...

and the King's School in

Canterbury Canterbury (, ) is a cathedral city and UNESCO World Heritage Site, situated in the heart of the City of Canterbury local government district of Kent, England. It lies on the River Stour. The Archbishop of Canterbury is the primate of ...

. He then studied Classics and Philosophy ("Greats") at

Merton College, Oxford Merton College (in full: The House or College of Scholars of Merton in the University of Oxford) is one of the constituent colleges of the University of Oxford in England. Its foundation can be traced back to the 1260s when Walter de Merton, ...

. On graduating in 1956 he did 18 months

National Service National service is the system of voluntary government service, usually military service. Conscription is mandatory national service. The term ''national service'' comes from the United Kingdom's National Service (Armed Forces) Act 1939. The ...

in the

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early medieval period, the first major maritime engagements were foug ...

, where he learned Russian. He returned to the

in 1958 to study for a postgraduate certificate in statistics, and it was here that he began

computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...

, having been taught Autocode on the Ferranti Mercury by

Leslie Fox Leslie Fox (30 September 1918 – 1 August 1992) was a British mathematician noted for his contribution to numerical analysis. Overview Fox studied mathematics as a scholar of Christ Church, Oxford graduating with a first in 1939 and continued ...

. He then went to

Moscow State University M. V. Lomonosov Moscow State University (MSU; russian: Московский государственный университет имени М. В. Ломоносова) is a public research university in Moscow, Russia and the most prestigious ...

as a

British Council The British Council is a British organisation specialising in international cultural and educational opportunities. It works in over 100 countries: promoting a wider knowledge of the United Kingdom and the English language (and the Welsh la ...

exchange student, where he studied

machine translation Machine translation, sometimes referred to by the abbreviation MT (not to be confused with computer-aided translation, machine-aided human translation or interactive translation), is a sub-field of computational linguistics that investigates t ...

under

Andrey Kolmogorov Andrey Nikolaevich Kolmogorov ( rus, Андре́й Никола́евич Колмого́ров, p=ɐnˈdrʲej nʲɪkɐˈlajɪvʲɪtɕ kəlmɐˈɡorəf, a=Ru-Andrey Nikolaevich Kolmogorov.ogg, 25 April 1903 – 20 October 1987) was a Sovi ...

Research and career

In 1960, Hoare left the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

and began working at Elliott Brothers Ltd, a small computer manufacturing firm located in London. There, he implemented the language

ALGOL 60 ALGOL 60 (short for ''Algorithmic Language 1960'') is a member of the ALGOL family of computer programming languages. It followed on from ALGOL 58 which had introduced code blocks and the begin and end pairs for delimiting them, representing a k ...

and began developing major

s. He was involved with developing international standards in programming and informatics, as a member of the

International Federation for Information Processing The International Federation for Information Processing (IFIP) is a global organisation for researchers and professionals working in the field of computing to conduct research, develop standards and promote information sharing. Established in 196 ...

(IFIP) Working Group 2.1 on Algorithmic Languages and Calculi, which specified, maintains, and supports the languages ALGOL 60 and

ALGOL 68 ALGOL 68 (short for ''Algorithmic Language 1968'') is an imperative programming language that was conceived as a successor to the ALGOL 60 programming language, designed with the goal of a much wider scope of application and more rigorously ...

. He became the Professor of Computing Science at the

Queen's University of Belfast , mottoeng = For so much, what shall we give back? , top_free_label = , top_free = , top_free_label1 = , top_free1 = , top_free_label2 = , top_free2 = , established = , closed = , type = Public research university , parent = ...

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 ''Emeritus'' (; female: ''emerita'') is an adjective used to designate a retired chair, professor, pastor, bishop, pope, director, president, prime minister, rabbi, emperor, or other person who has been "permitted to retain as an honorary title ...

there, and is also a principal researcher at Microsoft Research in

, England. Hoare's most significant work has been in the following areas: his sorting and selection algorithm (

Quicksort Quicksort is an efficient, general-purpose sorting algorithm. Quicksort was developed by British computer scientist Tony Hoare in 1959 and published in 1961, it is still a commonly used algorithm for sorting. Overall, it is slightly faster than ...

and Quickselect),

, the formal language communicating sequential processes (CSP) used to specify the interactions between concurrent processes (and implemented in various programming languages such as occam), structuring computer

s using the monitor concept, and the

axiom An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy o ...

atic specification of

programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming l ...

s. Speaking at a software conference in 2009, Tony Hoare apologized for inventing the null reference: For many years under his leadership, Hoare's Oxford department worked on formal specification languages such as

CSP CSP may refer to: Education * College Student Personnel, an academic discipline * Commonwealth Supported Place, a category in Australian education * Concordia University (Saint Paul, Minnesota), US Organizations * Caledonian Steam Packet Compa ...

and Z. These did not achieve the expected take-up by industry, and in 1995 Hoare was led to reflect upon the original assumptions:

Awards and honours

* Distinguished Fellow of the British Computer Society (1978) *

for "fundamental contributions to the definition and design of

s". The award was presented to him at the ACM Annual Conference in

Nashville, Tennessee Nashville is the capital city of the U.S. state of Tennessee and the seat of Davidson County. With a population of 689,447 at the 2020 U.S. census, Nashville is the most populous city in the state, 21st most-populous city in the U.S., and t ...

, on 27 October 1980, by Walter Carlson, chairman of the Awards committee. A transcript of Hoare's speech was published in ''

Communications of the ACM ''Communications of the ACM'' is the monthly journal of the Association for Computing Machinery (ACM). It was established in 1958, with Saul Rosen as its first managing editor. It is sent to all ACM members. Articles are intended for readers with ...

''. *

Harry H. Goode Memorial Award The Harry H. Goode Memorial Award is an IEEE Computer Society The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated discipline ...

(1981) *

Fellow of the Royal Society Fellowship of the Royal Society (FRS, ForMemRS and HonFRS) is an award granted by the judges of the Royal Society of London to individuals who have made a "substantial contribution to the improvement of natural knowledge, including mathematic ...

(1982) * Honorary Doctorate of Science by the

Queen's University Belfast , mottoeng = For so much, what shall we give back? , top_free_label = , top_free = , top_free_label1 = , top_free1 = , top_free_label2 = , top_free2 = , established = , closed = , type = Public research university , parent = ...

(1987) * Honorary Doctorate of Science, from the

University of Bath (Virgil, Georgics II) , mottoeng = Learn the culture proper to each after its kind , established = 1886 (Merchant Venturers Technical College) 1960 (Bristol College of Science and Technology) 1966 (Bath University of Technology) 1971 (univ ...

(1993) * Honorary Fellow,

Kellogg College, Oxford Kellogg College is a graduate-only constituent college of the University of Oxford in England. Founded in 1990 as Rewley House, Kellogg is the university's 36th college and the largest by number of students. It hosts research centres includin ...

(1998) * Knighted for services to education and

computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includin ...

(

2000 File:2000 Events Collage.png, From left, clockwise: Protests against Bush v. Gore after the 2000 United States presidential election; Heads of state meet for the Millennium Summit; The International Space Station in its infant form as seen from ...

) * Kyoto Prize for

Information science Information science (also known as information studies) is an academic field which is primarily concerned with analysis, collection, classification, manipulation, storage, retrieval, movement, dissemination, and protection of information. ...

(2000) *

Fellow A fellow is a concept whose exact meaning depends on context. In learned or professional societies, it refers to a privileged member who is specially elected in recognition of their work and achievements. Within the context of higher education ...

of the Royal Academy of Engineering (2005) * Member of the

National Academy of Engineering The National Academy of Engineering (NAE) is an American nonprofit, non-governmental organization. The National Academy of Engineering is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of ...

(2006) for fundamental contributions to computer science in the areas of algorithms, operating systems, and programming languages. *

Computer History Museum The Computer History Museum (CHM) is a museum of computer history, located in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the information age, and explores the computing revolution and its impact ...

(CHM) in

Mountain View, California Mountain View is a city in Santa Clara County, California, United States. Named for its views of the Santa Cruz Mountains, it has a population of 82,376. Mountain View was integral to the early history and growth of Silicon Valley, and is th ...

Fellow of the Museum "for development of the

algorithm and for lifelong contributions to the theory of

s" (2006) * Honorary Doctorate from

Heriot-Watt University Heriot-Watt University ( gd, Oilthigh Heriot-Watt) is a public research university based in Edinburgh, Scotland. It was established in 1821 as the School of Arts of Edinburgh, the world's first mechanics' institute, and subsequently granted uni ...

(2007) * Honorary Doctorate of Science from the Department of Informatics of the Athens University of Economics and Business (AUEB) (2007) * Friedrich L. Bauer-Prize,

Technical University of Munich The Technical University of Munich (TUM or TU Munich; german: Technische Universität München) is a public research university in Munich, Germany. It specializes in engineering, technology, medicine, and applied and natural sciences. Establis ...

(2007) * SIGPLAN Programming Languages Achievement Award (2011) * IEEE John von Neumann Medal (2011) * Honorary Doctorate,

University of Warsaw The University of Warsaw ( pl, Uniwersytet Warszawski, la, Universitas Varsoviensis) is a public university in Warsaw, Poland. Established in 1816, it is the largest institution of higher learning in the country offering 37 different fields of ...

(2012) * Honorary Doctorate,

Complutense University of Madrid The Complutense University of Madrid ( es, Universidad Complutense de Madrid; UCM, links=no, ''Universidad de Madrid'', ''Universidad Central de Madrid''; la, Universitas Complutensis Matritensis, links=no) is a public research university lo ...

(2013) * 1973 ACM Programming Systems and Languages Paper Award, for the paper "Proof of correctness of data representations"

Personal life

In 1962, Hoare married Jill Pym, a member of his research team.

Books

* * C. A. R. Hoare (1985). '' Communicating Sequential Processes''.

Prentice Hall Prentice Hall was an American major educational publisher owned by Savvas Learning Company. Prentice Hall publishes print and digital content for the 6–12 and higher-education market, and distributes its technical titles through the Safari B ...

International Series in Computer Science. (hardback) or (paperback). (Available online at http://www.usingcsp.com/ in PDF format.) * * *

References

External links

* {{DEFAULTSORT:Hoare, Tony 1934 births Living people People from Colombo People educated at The Dragon School People educated at The King's School, Canterbury Alumni of Merton College, Oxford Academics of Queen's University Belfast British computer scientists Fellows of the British Computer Society Fellows of the Royal Academy of Engineering Fellows of the Royal Society Foreign associates of the National Academy of Sciences Fellows of Wolfson College, Oxford Formal methods people History of computing in the United Kingdom Knights Bachelor Kyoto laureates in Advanced Technology Members of the Department of Computer Science, University of Oxford Microsoft employees Moscow State University alumni Programming language researchers Turing Award laureates Computer science writers British expatriates in Sri Lanka British expatriates in the Soviet Union Fellows of Merton College, Oxford