Sir Charles Antony Richard Hoare (; born 11 January 1934), also known as C. A. R. Hoare, is a British

computer scientist A computer scientist is a scientist who specializes in the academic study of computer science. Computer scientists typically work on the theoretical side of computation. Although computer scientists can also focus their work and research on ...

who has made foundational contributions to

programming languages A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their syntax (form) and semantics (meaning), usually defined by a formal language. Languages usually provide features ...

algorithm In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...

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

formal verification In the context of hardware and software systems, formal verification is the act of proving or disproving the correctness of a system with respect to a certain formal specification or property, using formal methods of mathematics. Formal ver ...

, 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 syst ...

. 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 the fi ...

, 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 (computing), list into an Total order, order. The most frequently used orders are numerical order and lexicographical order, and either ascending or descending ...

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 l ...

, an axiomatic 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: for each input it produ ...

. In the semantics of concurrency, he introduced the formal language

communicating sequential processes In computer science, communicating sequential processes (CSP) is a formal language for describing patterns of interaction in concurrent systems. It is a member of the family of mathematical theories of concurrency known as process algebras, or p ...

(CSP) to specify the interactions of concurrent processes, and along with

Edsger Dijkstra Edsger Wybe Dijkstra ( ; ; 11 May 1930 – 6 August 2002) was a Dutch computer scientist, programmer, software engineer, mathematician, and science essayist. Born in Rotterdam in the Netherlands, Dijkstra studied mathematics and physics and the ...

, formulated the

dining philosophers problem In computer science, the dining philosophers problem is an example problem often used in concurrent algorithm design to illustrate synchronization issues and techniques for resolving them. It was originally formulated in 1965 by Edsger Dijkstra ...

. Since 1977, he has held positions at the

University of Oxford The University of Oxford is a collegiate university, 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 List of oldest un ...

and

Microsoft Research Microsoft Research (MSR) is the research subsidiary of Microsoft. It was created in 1991 by Richard Rashid, Bill Gates and Nathan Myhrvold with the intent to advance state-of-the-art computing and solve difficult world problems through technologi ...

Cambridge Cambridge ( ) is a List of cities in the United Kingdom, city and non-metropolitan district in the county of Cambridgeshire, England. It is the county town of Cambridgeshire and is located on the River Cam, north of London. As of the 2021 Unit ...

Education and early life

Tony Hoare was born in

Colombo Colombo, ( ; , ; , ), is the executive and judicial capital and largest city of Sri Lanka by population. The Colombo metropolitan area is estimated to have a population of 5.6 million, and 752,993 within the municipal limits. It is the ...

, Ceylon (now

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

) 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 service personnel hired rather than elected, whose institutional tenure typically survives transitions of political leadership. A civil service offic ...

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

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

at the

Dragon School The Dragon School is a private school across two sites in Oxford, England. The Dragon Pre-Prep (children aged 4–7) and Prep School (children aged 8–13) are both co-educational schools. The Dragon Prep School was founded in 1877 as the Oxfo ...

Oxford Oxford () is a City status in the United Kingdom, cathedral city and non-metropolitan district in Oxfordshire, England, of which it is the county town. The city is home to the University of Oxford, the List of oldest universities in continuou ...

and the King's School in

Canterbury Canterbury (, ) is a City status in the United Kingdom, city and UNESCO World Heritage Site, in the county of Kent, England; it was a county borough until 1974. It lies on the River Stour, Kent, River Stour. The city has a mild oceanic climat ...

. 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 a Colleges of the University of Oxford, constituent college of the University of Oxford in England. Its foundation can be traced back to the 126 ...

. On graduating in 1956 he did 18 months

National Service National service is a system of compulsory or 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 ...

in the

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

, where he learned Russian. He returned to the

in 1958 to study for a postgraduate certificate in

statistics Statistics (from German language, German: ', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a s ...

, and it was here that he began

computer programming Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of proc ...

, having been taught

Autocode Autocode is the name of a family of "simplified coding systems", later called programming languages, devised in the 1950s and 1960s for a series of digital computers at the Universities of Manchester, Cambridge and London. Autocode was a generi ...

on the

Ferranti Mercury The Mercury was an early commercial computer from the mid-1950s built by Ferranti. It was the successor to the Ferranti Mark 1, adding a floating point unit for improved performance, and increased reliability by replacing the Williams tube memor ...

by Leslie Fox. He then went to

Moscow State University Moscow State University (MSU), officially M. V. Lomonosov Moscow State University,. is a public university, public research university in Moscow, Russia. The university includes 15 research institutes, 43 faculties, more than 300 departments, a ...

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 lang ...

exchange student, where he studied

machine translation Machine translation is use of computational techniques to translate text or speech from one language to another, including the contextual, idiomatic and pragmatic nuances of both languages. Early approaches were mostly rule-based or statisti ...

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 Soviet ...

Research and career

In 1960, Hoare left the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

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 ...

and began developing major

s. He was involved with developing

international standard An international standard is a technical standard developed by one or more international standards organizations. International standards are available for consideration and use worldwide. The most prominent such organization is the International O ...

s 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 19 ...

(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 member of the ALGOL family that was conceived as a successor to the ALGOL 60 language, designed with the goal of a much wider scope of application and ...

. He became the Professor of

Computing Science Computer science is the study of computation, information, and automation. Computer science spans theoretical disciplines (such as algorithms, theory of computation, and information theory) to applied disciplines (including the design an ...

at the

Queen's University of Belfast The Queen's University of Belfast, commonly known as Queen's University Belfast (; abbreviated Queen's or QUB), is a public research university in Belfast, Northern Ireland, United Kingdom. The university received its charter in 1845 as part of ...

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 Christopher S. Strachey (; 16 November 1916 – 18 May 1975) was a British computer scientist. He was one of the founders of denotational semantics, and a pioneer in programming language design and computer time-sharing.F. J. Corbató, et al., T ...

. He became the first Christopher Strachey Professor of Computing on its establishment in 1988 until his retirement at Oxford in 2000. He is now an

Emeritus Professor ''Emeritus/Emerita'' () is an honorary title granted to someone who retires from a position of distinction, most commonly an academic faculty position, but is allowed to continue using the previous title, as in "professor emeritus". In some c ...

there, and is also a principal researcher at

, 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 In computer science, quickselect is a selection algorithm to find the ''k''th smallest element in an unordered list, also known as the ''k''th order statistic. Like the related quicksort sorting algorithm, it was developed by Tony Hoare, and t ...

, the formal language

(CSP) used to specify the interactions between

concurrent process 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 syste ...

es (and implemented in various programming languages such as occam), structuring computer

s using the

monitor Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, Wes ...

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 or ...

atic specification of

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

s. Speaking at a software conference in 2009, Tony Hoare hyperbolically apologized for inventing the null reference: For many years under his leadership, Hoare's 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: A commemorative article was written in tribute to Hoare for his 90th birthday.

Awards and honours

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

Distinguished Fellow of the British Computer Society Distinguished Fellow of the British Computer Society (DFBCS or DistFBCS) is an award and fellowship granted by the British Computer Society for members of the computing profession who have made an outstanding contribution to the advancement of co ...

(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, often known as Music City, is the capital and List of municipalities in Tennessee, most populous city in the U.S. state of Tennessee. It is the county seat, seat of Davidson County, Tennessee, Davidson County in Middle Tennessee, locat ...

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

''. * Harry H. Goode Memorial Award (1981) *

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

(1982) * Honorary Doctorate of Science by the

Queen's University Belfast The Queen's University of Belfast, commonly known as Queen's University Belfast (; abbreviated Queen's or QUB), is a public research university in Belfast, Northern Ireland, United Kingdom. The university received its charter in 1845 as part of ...

(1987) * Honorary Doctorate of Science, from the

University of Bath The University of Bath is a public research university in Bath, England. Bath received its royal charter in 1966 as Bath University of Technology, along with a number of other institutions following the Robbins Report. Like the University ...

(1993) * Honorary Fellow,

Kellogg College, Oxford Kellogg College is a graduate-only colleges of the University of Oxford, 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 ...

(1998) *

Knighted A knight is a person granted an honorary title of a knighthood by a head of state (including the pope) or representative for service to the monarch, the church, or the country, especially in a military capacity. The concept of a knighthood ...

for services to education and

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

(

2000 2000 was designated as the International Year for the Culture of Peace and the World Mathematics, Mathematical Year. Popular culture holds the year 2000 as the first year of the 21st century and the 3rd millennium, because of a tende ...

) *

Kyoto Prize The is Japan's highest private award for lifetime achievement in the arts and sciences. It is given not only to those that are top representatives of their own respective fields, but to "those who have contributed significantly to the scientific, ...

for Information science (2000) *

Fellow A fellow is a title and form of address for distinguished, learned, or skilled individuals in academia, medicine, research, and industry. The exact meaning of the term differs in each field. In learned society, learned or professional society, p ...

of the

Royal Academy of Engineering The Royal Academy of Engineering (RAEng) is the United Kingdom's national academy of engineering. The Academy was founded in June 1976 as the Fellowship of Engineering with support from Prince Philip, Duke of Edinburgh, who became the first senio ...

(2005) * Member of the

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

(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 computer museum in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the Information Age, and explores the Digital Revolution, computing revolution and its impact ...

(CHM) in

Mountain View, California Mountain View is a city in Santa Clara County, California, United States, part of the San Francisco Bay Area. Named for its views of the Santa Cruz Mountains, the population was 82,376 at the 2020 United States census, 2020 census. Mountain V ...

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 () 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 was subsequently granted university status by roya ...

(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; ) is a public research university in Munich, Bavaria, Germany. It specializes in engineering, technology, medicine, and applied and natural sciences. Established in 1868 by King Ludwig II ...

(2007) *

SIGPLAN SIGPLAN is the Association for Computing Machinery's Special Interest Group (SIG) on programming languages. This SIG explores programming language concepts and tools, focusing on design, implementation, practice, and theory. Its members are progra ...

Programming Languages Achievement Award (2011) *

IEEE John von Neumann Medal The IEEE John von Neumann Medal was established by the IEEE Board of Directors in 1990 and may be presented annually "for outstanding achievements in computer-related science and technology." The achievements may be theoretical, technological, or ...

(2011) * Honorary Doctorate,

University of Warsaw The University of Warsaw (, ) is a public university, public research university in Warsaw, Poland. Established on November 19, 1816, it is the largest institution of higher learning in the country, offering 37 different fields of study as well ...

(2012) * Honorary Doctorate,

Complutense University of Madrid The Complutense University of Madrid (, UCM; ) is a public research university located in Madrid. Founded in Alcalá in 1293 (before relocating to Madrid in 1836), it is one of the oldest operating universities in the world, and one of Spain's ...

(2013) *

Royal Medal The Royal Medal, also known as The Queen's Medal and The King's Medal (depending on the gender of the monarch at the time of the award), is a silver-gilt medal, of which three are awarded each year by the Royal Society. Two are given for "the mo ...

of the Royal Society (2023)

Personal life

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

Books

* * C. A. R. Hoare (1985). ''

Communicating Sequential Processes In computer science, communicating sequential processes (CSP) is a formal language for describing patterns of interaction in concurrent systems. It is a member of the family of mathematical theories of concurrency known as process algebras, or p ...

''.

Prentice Hall Prentice Hall was a major American publishing#Textbook_publishing, educational publisher. It published print and digital content for the 6–12 and higher-education market. It was an independent company throughout the bulk of the twentieth cen ...

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 Scientists 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