**Alan Mathison Turing**, OBE

, FRS (icon ; 23 June 1912 – 7 June 1954), was an English mathematician

, logician, cryptanalyst, and computer scientist

. He was highly influential in the development of computer science

, providing a formalisation of the concepts of "algorithm

" and "computation" with the Turing machine

, which played a significant role in the creation of the modern computer. Turing is widely considered to be the father of computer science and artificial intelligence

. He was stockily built, had a high-pitched voice, and was talkative, witty, and somewhat donnish

.

During the Second World War

, Turing worked for the Government Code and Cypher School at Bletchley Park

, Britain's codebreaking

centre.

A man provided with paper, pencil, and rubber, and subject to strict discipline, is in effect a Turing machine|universal machine.

The idea behind digital computers may be explained by saying that these machines are intended to carry out any operations which could be done by a human computer.

I believe that at the end of the century the use of words and general educated opinion will have altered so much that one will be able to speak of machines thinking without expecting to be contradicted.

I am not very impressed with theological arguments whatever they may be used to support. Such arguments have often been found unsatisfactory in the past. In the time of Galileo Galilei|Galileo it was argued that the texts, "And the sun stood still... and hasted not to go down about a whole day" (Joshua x. 13) and "He laid the foundations of the earth, that it should not move at any time" (Psalm cv. 5) were an adequate refutation of the Copernican theory.

We can only see a short distance ahead, but we can see plenty there that needs to be done.

**Alan Mathison Turing**, OBE

, FRS (icon ; 23 June 1912 – 7 June 1954), was an English mathematician

, logician, cryptanalyst, and computer scientist

. He was highly influential in the development of computer science

, providing a formalisation of the concepts of "algorithm

" and "computation" with the Turing machine

, which played a significant role in the creation of the modern computer. Turing is widely considered to be the father of computer science and artificial intelligence

. He was stockily built, had a high-pitched voice, and was talkative, witty, and somewhat donnish

.

During the Second World War

, Turing worked for the Government Code and Cypher School at Bletchley Park

, Britain's codebreaking

centre. For a time he was head of Hut 8

, the section responsible for German naval cryptanalysis

. He devised a number of techniques for breaking German cipher

s, including the method of the bombe

, an electromechanical

machine that could find settings for the Enigma machine

. After the war he worked at the National Physical Laboratory

, where he created one of the first designs for a stored-program computer, the ACE.

In 1948 Turing joined Max Newman's

Computing Laboratory at Manchester University

, where he assisted in the development of the Manchester computers

and became interested in mathematical biology

. He wrote a paper on the chemical basis of morphogenesis

, and he predicted oscillating

chemical reaction

s such as the Belousov–Zhabotinsky reaction, which were first observed in the 1960s.

Turing's homosexuality

resulted in a criminal prosecution in 1952, when homosexual acts were still illegal in the United Kingdom. He accepted treatment with female hormones (chemical castration

) as an alternative to prison. He died in 1954, just over two weeks before his 42nd birthday, from cyanide

poisoning. An inquest determined it was suicide; his mother and some others believed his death was accidental. On 10 September 2009, following an Internet campaign, British Prime Minister

Gordon Brown

made an official public apology on behalf of the British government for the way in which Turing was treated after the war.

## Childhood and youth

Alan Turing was conceived at Chhatrapur, Orissa

, India

. His father, Julius Mathison Turing, was a member of the Indian Civil Service. Julius and wife Ethel Sara Stoney (1881–1976, daughter of Edward Waller Stoney, chief engineer of the Madras Railways)

wanted Alan to be brought up in England, so they returned to Maida Vale

, London, where Alan Turing was born on 23 June 1912, as recorded by a blue plaque

on the outside of the building, later the Colonnade Hotel

. He had an elder brother, John. His father's civil service commission was still active, and during Turing's childhood years his parents travelled between Hastings

, England and India, leaving their two sons to stay with a retired Army couple. Very early in life, Turing showed signs of the genius he was to later prominently display.

His parents enrolled him at St Michael's, a day school at 20 Charles Road, St Leonards-on-Sea

, at the age of six. The headmistress recognised his talent early on, as did many of his subsequent educators. In 1926, at the age of 14, he went on to Sherborne School

, a famous independent school in the market town

of Sherborne

in Dorset

. His first day of term coincided with the 1926 General Strike

in Britain, but so determined was he to attend his first day that he rode his bicycle unaccompanied more than 60 miles (96.6 km) from Southampton

to school, stopping overnight at an inn.

Turing's natural inclination toward mathematics

and science did not earn him respect with some of the teachers at Sherborne, whose definition of education placed more emphasis on the classics

. His headmaster wrote to his parents: "I hope he will not fall between two stools. If he is to stay at Public School, he must aim at becoming

*educated*. If he is to be solely a

*Scientific Specialist*, he is wasting his time at a Public School". Despite this, Turing continued to show remarkable ability in the studies he loved, solving advanced problems in 1927 without having even studied elementary calculus

. In 1928, aged 16, Turing encountered Albert Einstein

's work; not only did he grasp it, but he extrapolated Einstein's questioning of Newton's laws of motion

from a text in which this was never made explicit.

Turing's hopes and ambitions at school were raised by the close friendship he developed with a slightly older fellow student, Christopher Morcom, who was Turing's first love interest. Morcom died on 13th February 1930suddenly, only a few weeks into their last term at Sherborne, from complications of bovine tuberculosis, contracted after drinking infected cow's milk as a boy. Turing's religious faith was shattered and he became an atheist. He adopted the conviction that all phenomena, including the workings of the human brain, must be materialistic

, but he still believed in the survival of the spirit after death.

## University and work on computability

After Sherborne, Turing went to study at King's College, Cambridge. He was an undergraduate there from 1931 to 1934, graduating with first-class honours in Mathematics

, and in 1935 was elected a fellow

at King's on the strength of a dissertation on the central limit theorem

.

In 1928, German mathematician David Hilbert

had called attention to the

*EntscheidungsproblemEntscheidungsproblemIn mathematics, the is a challenge posed by David Hilbert in 1928. The asks for an algorithm that will take as input a description of a formal language and a mathematical statement in the language and produce as output either "True" or "False" according to whether the statement is true or false...*

(decision problem). In his momentous paper "On Computable Numbers, with an Application to the

*Entscheidungsproblem*" (submitted on 28 May 1936 and delivered 12 November), Turing reformulated Kurt Gödel

's 1931 results on the limits of proof and computation, replacing Gödel's universal arithmetic-based formal language with what became known as Turing machine

s, formal and simple devices. He proved that some such machine would be capable of performing any conceivable mathematical computation if it were representable as an algorithm

. He went on to prove that there was no solution to the

*Entscheidungsproblem*by first showing that the halting problem

for Turing machines is undecidable

: it is not possible to decide, in general, algorithmically whether a given Turing machine will ever halt. While his proof was published subsequent to Alonzo Church's

equivalent proof in respect to his lambda calculus

, Turing was unaware of Church's work at the time.

Turing's approach is considerably more accessible and intuitive. It was also novel in its notion of a 'Universal (Turing) Machine', the idea that such a machine could perform the tasks of any other machine, or in other words, is provably capable of computing anything that is computable. Turing machines are to this day a central object of study in theory of computation

.

In his memoirs Turing wrote that he was disappointed about the reception of this 1936 paper and that only two people had reacted – these being Heinrich Scholz and Richard Bevan Braithwaite

.

The paper also introduces the notion of definable number

s.

From September 1936 to July 1938 he spent most of his time at the Institute for Advanced Study

, Princeton

, New Jersey, studying under Alonzo Church

. In addition to his purely mathematical work, he studied cryptology and also built three of four stages of an electro-mechanical binary multiplier. In June 1938 he obtained his PhD from Princeton; his dissertation (

*Systems of Logic Based on OrdinalsSystems of Logic Based on OrdinalsSystems of Logic Based on Ordinals was the PhD dissertation of the mathematician Alan Turing.The thesis was completed at Princeton under Alonzo Church and was a classic work in mathematics which introduced the concept of ordinal logic....*

) introduced the concept of ordinal logic

and the notion of relative computing

, where Turing machines are augmented with so-called oracles

, allowing a study of problems that cannot be solved by a Turing machine.

Back in Cambridge, he attended lectures by Ludwig Wittgenstein

about the foundations of mathematics

. The two argued and disagreed, with Turing defending formalism and Wittgenstein arguing that mathematics does not discover any absolute truths but rather invents them. He also started to work part-time with the Government Code and Cypher School (GCCS)

.

## Cryptanalysis

During the Second World War, Turing was a leading participant in the efforts at Bletchley Parkto break German ciphers. Building on cryptanalysis work carried out in Poland by Marian Rejewski

, Jerzy Różycki

and Henryk Zygalski

from Cipher Bureau before the war, he contributed several insights into breaking both the Enigma machine

and the Lorenz SZ 40/42 (a Teleprinter

cipher attachment codenamed

*Tunny*by the British), and was, for a time, head of Hut 8

, the section responsible for reading German naval signals.

From September 1938, Turing had been working part-time (notionally for the British Foreign Office

) with the Government Code and Cypher School (GCCS), the British code breaking organisation. He worked on the problem of the German Enigma machine, and collaborated with Dilly Knox

, a senior GCCS

codebreaker. On 4 September 1939, the day after the UK declared war on Germany, Turing reported to Bletchley Park, the wartime station of GCCS.

In 1945, Turing was awarded the OBE

for his wartime services, but his work remained secret for many years.

Turing had something of a reputation for eccentricity at Bletchley Park. Jack Good, a cryptanalyst who worked with him, is quoted by Ronald Lewin as having said of Turing:

in the first week of June each year he would get a bad attack of hay fever, and he would cycle to the office wearing a service gas mask to keep the pollen off. His bicycle had a fault: the chain would come off at regular intervals. Instead of having it mended he would count the number of times the pedals went round and would get off the bicycle in time to adjust the chain by hand. Another of his eccentricities is that he chained his mug to the radiator pipes to prevent it being stolen.

While working at Bletchley, Turing, a talented long-distance runner, occasionally ran the 40 miles (64.4 km) to London when he was needed for high-level meetings, and he was capable of world-class marathon standards.

### Turing–Welchman bombe

Within weeks of arriving at Bletchley Park, Turing had specified an electromechanical machine which could help break Enigma faster than bombafrom 1938, the bombe

, named after and building upon the original Polish-designed bomba. The bombe, with an enhancement suggested by mathematician Gordon Welchman

, became one of the primary tools, and the major automated one, used to attack Enigma-protected message traffic.

Jack Good opined:

Turing's most important contribution, Ithink, was of part of the design of the bombe, the cryptanalytic machine. He had the idea that you could use, in effect, a theorem in logic which sounds to the untrained ear rather absurd; namely that from a contradiction, you can deduceeverything.

The bombe searched for possibly correct settings used for an Enigma message (i.e., rotor order, rotor settings, etc.), and used a suitable

*crib*: a fragment of probable plaintext

. For each possible setting of the rotors (which had of the order of 10

^{19}states, or 10

^{22}for the four-rotor U-boat variant), the bombe performed a chain of logical deductions based on the crib, implemented electrically. The bombe detected when a contradiction had occurred, and ruled out that setting, moving onto the next. Most of the possible settings would cause contradictions and be discarded, leaving only a few to be investigated in detail. Turing's bombe was first installed on 18 March 1940. More than two hundred bombes were in operation by the end of the war.

### Hut 8 and Naval Enigma

Turing decided to tackle the particularly difficult problem of German naval Enigma "because no one else was doing anything about it and I could have it to myself". In December 1939, Turing solved the essential part of the naval indicator system, which was more complex than the indicator systems used by the other services. The same night that he solved the naval indicator system, he conceived the idea of*BanburismusBanburismusBanburismus was a cryptanalytic process developed by Alan Turing at Bletchley Park in England during the Second World War. It was used by Bletchley Park's Hut 8 to help break German Kriegsmarine messages enciphered on Enigma machines. The process used sequential conditional probability to infer...*

, a sequential statistical technique (what Abraham Wald

later called sequential analysis

) to assist in breaking naval Enigma, "though I was not sure that it would work in practice, and was not in fact sure until some days had actually broken". For this he invented a measure of weight of evidence that he called the

*BanBan (information)A ban, sometimes called a hartley or a dit , is a logarithmic unit which measures information or entropy, based on base 10 logarithms and powers of 10, rather than the powers of 2 and base 2 logarithms which define the bit. As a bit corresponds to a binary digit, so a ban is a decimal digit...*

. Banburismus could rule out certain orders of the Enigma rotors, substantially reducing the time needed to test settings on the bombes.

In 1941, Turing proposed marriage to Hut 8 co-worker Joan Clarke, a fellow mathematician, but their engagement was short-lived. After admitting his homosexuality to his fiancée, who was reportedly "unfazed" by the revelation, Turing decided that he could not go through with the marriage.

In July 1942, Turing devised a technique termed

*TuringeryTuringeryTuringery or Turing's Method was a hand codebreaking method devised by the mathematician and cryptanalyst Alan Turing at the British Government Code and Cypher School at Bletchley Park during World War II...*

(or jokingly

*Turingismus*) for use against the Lorenz cipher

messages produced by the Germans' new Geheimschreiber machine (

*secret writer*). This was codenamed

*Tunny*at Bletchley Park. He also introduced the Tunny team to Tommy Flowers

who, under the guidance of Max Newman

, went on to build the Colossus computer

, the world's first programmable digital electronic computer, which replaced a simpler prior machine (the Heath Robinson

) and whose superior speed allowed the brute-force decryption techniques to be applied usefully to the daily changing cyphers. A frequent misconception is that Turing was a key figure in the design of Colossus; this was not the case.

Turing travelled to the United States in November 1942 and worked with U.S. Navy cryptanalysts on Naval Enigma and bombe construction in Washington, and assisted at Bell Labs

with the development of secure speech devices. He returned to Bletchley Park in March 1943. During his absence, Hugh Alexander

had officially assumed the position of head of Hut 8, although Alexander had been

*de facto*head for some time—Turing having little interest in the day-to-day running of the section. Turing became a general consultant for cryptanalysis at Bletchley Park.

Alexander wrote as follows about his contribution:

There should be no question in anyone's mind that Turing's work was the biggest factor in Hut 8's success. In the early days he was the only cryptographer who thought the problem worth tackling and not only was he primarily responsible for the main theoretical work within the Hut but he also shared with Welchman and Keen the chief credit for the invention of the Bombe. It is always difficult to say that anyone is absolutely indispensable but if anyone was indispensable to Hut 8 it was Turing. The pioneer's work always tends to be forgotten when experience and routine later make everything seem easy and many of us in Hut 8 felt that the magnitude of Turing's contribution was never fully realised by the outside world.

In the latter part of the war he moved to work at Hanslope Park, where he further developed his knowledge of electronics with the assistance of engineer Donald Bayley. Together they undertook the design and construction of a portable secure voice

communications machine codenamed

*Delilah*. It was intended for different applications, lacking capability for use with long-distance radio transmissions, and in any case, Delilah was completed too late to be used during the war. Though Turing demonstrated it to officials by encrypting/decrypting a recording of a Winston Churchill

speech, Delilah was not adopted for use. Turing also consulted with Bell Labs

on the development of SIGSALY

, a secure voice system that was used in the later years of the war.

## Early computers and the Turing test

From 1945 to 1947 Turing lived in Church Street, Hampton while he worked on the design of the ACE(Automatic Computing Engine) at the National Physical Laboratory

. He presented a paper on 19 February 1946, which was the first detailed design of a stored-program computer

. Although ACE was a feasible design, the secrecy surrounding the wartime work at Bletchley Park led to delays in starting the project and he became disillusioned. In late 1947 he returned to Cambridge for a sabbatical year. While he was at Cambridge, the Pilot ACE

was built in his absence. It executed its first program on 10 May 1950.

In 1948, he was appointed Reader

in the Mathematics Department

at Manchester

(now part of The University of Manchester). In 1949, he became Deputy Director of the computing laboratory at the University of Manchester

, and worked on software for one of the earliest stored-program

computers—the Manchester Mark 1

. During this time he continued to do more abstract work, and in "Computing machinery and intelligence

" (Mind, October 1950), Turing addressed the problem of artificial intelligence

, and proposed an experiment which became known as the Turing test

, an attempt to define a standard for a machine to be called "intelligent". The idea was that a computer could be said to "think" if a human interrogator could not tell it apart, through conversation, from a human being. In the paper, Turing suggested that rather than building a program to simulate the adult mind, it would be better rather to produce a simpler one to simulate a child's mind and then to subject it to a course of education. A reversed form of the Turing test is widely used on the Internet; the CAPTCHA

test is intended to determine whether the user is a human or a computer.

In 1948, Turing, working with his former undergraduate colleague, D. G. Champernowne

, began writing a chess

program for a computer that did not yet exist. In 1952, lacking a computer powerful enough to execute the program, Turing played a game in which he simulated the computer, taking about half an hour per move. The game was recorded. The program lost to Turing's colleague Alick Glennie

, although it is said that it won a game against Champernowne's wife.

His Turing test

was a significant and characteristically provocative and lasting contribution to the debate regarding artificial intelligence

, which continues after more than half a century.

He also invented the LU decomposition

method in 1948, used today for solving an equations matrix.

## Pattern formation and mathematical biology

Turing worked from 1952 until his death in 1954 on mathematical biology, specifically morphogenesis

. He published one paper on the subject called

*The Chemical Basis of MorphogenesisThe chemical basis of morphogenesisThe Chemical Basis of Morphogenesis is an article written by Alan Turing in 1951 describing the way in which non-uniformity may arise naturally out of a homogeneous, uniform state....*

in 1952, putting forth the Turing hypothesis of pattern formation. His central interest in the field was understanding Fibonacci phyllotaxis

, the existence of Fibonacci number

s in plant structures. He used reaction–diffusion equations which are central to the field of pattern formation

. Later papers went unpublished until 1992 when

*Collected Works of A.M. Turing*was published. His contribution is considered a seminal piece of work in this field.

## Conviction for indecency

In January 1952, Turing met Arnold Murray outside a cinema in Manchester. After a lunch date, Turing invited Murray to spend the weekend with him at his house, an invitation which Murray accepted although he did not show up. The pair met again in Manchester the following Monday, when Murray agreed to accompany Turing to the latter's house. A few weeks later Murray visited Turing's house again, and apparently spent the night there.After Murray helped an accomplice to break into his house, Turing reported the crime to the police. During the investigation, Turing acknowledged a sexual relationship with Murray. Homosexual acts were illegal in the United Kingdom at that time, and so both were charged with gross indecency under Section 11 of the Criminal Law Amendment Act 1885

.

Turing was given a choice between imprisonment or probation conditional on his agreement to undergo hormonal

treatment

designed to reduce libido

. He accepted chemical castration

via oestrogen hormone injections.

Turing's conviction led to the removal of his security clearance, and barred him from continuing with his cryptographic consultancy for GCHQ. At the time, there was acute public anxiety about spies and homosexual entrapment by Soviet agents, because of the recent exposure of the first two members of the Cambridge Five

, Guy Burgess

and Donald Maclean

, as KGB

double agent

s. Turing was never accused of espionage but, as with all who had worked at Bletchley Park

, was prevented from discussing his war work.

## Death

On 8 June 1954, Turing's cleaner found him dead; he had died the previous day. A post-mortem examination established that the cause of death was cyanide poisoning. When his body was discovered an apple lay half-eaten beside his bed, and although the apple was not tested for cyanide, it is speculated that this was the means by which a fatal dose was delivered. An inquestdetermined that he had committed suicide, and he was cremated at Woking Crematorium

on 12 June 1954. Turing's mother argued strenuously that the ingestion was accidental, caused by her son's careless storage of laboratory chemicals. Biographer Andrew Hodges

suggests that Turing may have killed himself in an ambiguous way quite deliberately, to give his mother some plausible deniability

. David Leavitt has suggested that Turing was re-enacting a scene from the 1937 film

*Snow WhiteSnow White and the Seven Dwarfs (1937 film)Snow White and the Seven Dwarfs is a 1937 American animated film based on Snow White, a German fairy tale by the Brothers Grimm. It was the first full-length cel-animated feature in motion picture history, as well as the first animated feature film produced in America, the first produced in full...*

, his favourite fairy tale

, pointing out that he took "an especially keen pleasure in the scene where the Wicked Witch immerses her apple in the poisonous brew."

### Epitaph

## Recognition and tributes

A biography published by the Royal Society shortly after Turing's death (and while his wartime work was still subject to the Official Secrets Act) recorded:

Three remarkable papers written just before the war, on three diverse mathematical subjects, show the quality of the work that might have been produced if he had settled down to work on some big problem at that critical time. For his work at the Foreign Office he was awarded the OBE.

Since 1966, the Turing Award

has been given annually by the Association for Computing Machinery

to a person for technical contributions to the computing community. It is widely considered to be the computing world's highest honour, equivalent to the Nobel Prize.

*Breaking the CodeBreaking the CodeBreaking the Code is a 1986 play by Hugh Whitemore about British mathematician Alan Turing, who was a key player in the breaking of the German Enigma code at Bletchley Park during World War II...*

is a 1986 play by Hugh Whitemore

about Alan Turing. The play ran in London's West End

beginning in November 1986 and on Broadway from 15 November 1987 to 10 April 1988. There was also a 1996 BBC television production. In all cases, Derek Jacobi

played Turing. The Broadway production was nominated for three Tony Award

s including Best Actor in a Play, Best Featured Actor in a Play, and Best Direction of a Play, and for two Drama Desk Award

s, for Best Actor and Best Featured Actor.

On 23 June 1998, on what would have been Turing's 86th birthday, Andrew Hodges

, his biographer, unveiled an official English Heritage

Blue Plaque

at his birthplace and childhood home in Warrington Crescent, London, later the Colonnade Hotel.

To mark the 50th anniversary of his death, a memorial plaque was unveiled on 7 June 2004 at his former residence, Hollymeade, in Wilmslow

, Cheshire

.

On 13 March 2000, Saint Vincent and the Grenadines

issued a set of stamps

to celebrate the greatest achievements of the 20th century, one of which carries a recognisable portrait of Turing against a background of repeated 0s and 1s, and is captioned: "1937: Alan Turing's theory of digital computing".

On 28 October 2004, a bronze statue of Alan Turing sculpted by John W. Mills

was unveiled at the University of Surrey

in Guildford

, marking the 50th anniversary of Turing's death; it portrays him carrying his books across the campus.

In 2006, Boston Pride named Turing their Honorary Grand Marshal.

Turing was one of four mathematicians examined in the 2008 BBC documentary entitled "Dangerous Knowledge".

The Princeton Alumni Weekly named Turing the second most significant alumnus in the history of Princeton University

, second only to President James Madison

.

A 1.5-ton, life-size statue of Turing was unveiled on 19 June 2007 at Bletchley Park. Built from approximately half a million pieces of Welsh

slate

, it was sculpted by Stephen Kettle

, having been commissioned by the late American billionaire Sidney Frank

.

Turing has been honoured in various ways in Manchester

, the city where he worked towards the end of his life. In 1994, a stretch of the A6010 road (the Manchester

city intermediate ring road) was named

*"Alan Turing Way"*. Part of this road runs alongside the City of Manchester Stadium

, where Manchester City play their games. A bridge carrying this road was widened, and carries the name Alan Turing Bridge. A statue of Turing

was unveiled in Manchester on 23 June 2001. It is in Sackville Park, between the University of Manchester

building on Whitworth Street and the Canal Street gay village

. The memorial statue, depicts the "father of Computer Science" sitting on a bench at a central position in the park. The statue was unveiled on Turing's birthday.

Turing is shown holding an apple—a symbol classically used to represent forbidden love, the object that inspired Isaac Newton

's theory of gravitation, and the means of Turing's own death. The cast bronze bench carries in relief the text 'Alan Mathison Turing 1912–1954', and the motto 'Founder of Computer Science' as it would appear if encoded by an Enigma machine

: 'IEKYF ROMSI ADXUO KVKZC GUBJ'.

A plinth at the statue's feet says 'Father of computer science, mathematician, logician, wartime codebreaker, victim of prejudice'. There is also a Bertrand Russell

quotation saying 'Mathematics, rightly viewed, possesses not only truth, but supreme beauty—a beauty cold and austere, like that of sculpture.' The sculptor buried his old Amstrad

computer, which was an early popular home computer, under the plinth, as a tribute to "the godfather of all modern computers".

In 1999,

*Time Magazine*named Turing as one of the 100 Most Important People of the 20th century

for his role in the creation of the modern computer, and stated: "The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine." Turing is featured in the 1999 Neal Stephenson

novel "Cryptonomicon

."

In 2002, Turing was ranked twenty-first on the

*BBC*nationwide poll of the 100 Greatest Britons

.

The logo of Apple computer is often erroneously referred to as a tribute to Alan Turing, with the bite mark a reference to his method of suicide. Both the designer of the logo and the company deny that there is any homage to Turing in the design of the logo.

In 2010, actor/playwright Jade Esteban Estrada portrayed Turing in the solo musical, "ICONS: The Lesbian and Gay History of the World, Vol. 4."

Turing is mentioned several times in the DLC for the 2K Games "Bioshock 2" He is mentioned several times by the voice actor who portrays C. M. Porter. There is also a telegram in Porter's office requesting he come to London and work with Turing. He is also mentioned in Assassin's Creed: Brotherhood

, when an employee of Abstergo Industries orders him to be killed and commands the would-be executioner to "make it look biblical".

In February 2011, Turing's papers from the Second World War were bought for the nation with an 11th-hour bid by the National Heritage Memorial Fund

, allowing them to stay at Bletchley Park.

### Government apology

In August 2009, John Graham-Cummingstarted a petition urging the British Government to posthumously apologise to Alan Turing for prosecuting him as a homosexual. The petition received thousands of signatures. Prime Minister Gordon Brown

acknowledged the petition, releasing a statement on 10 September 2009 apologising and describing Turing's treatment as "appalling":

Thousands of people have come together to demand justice for Alan Turing and recognition of the appalling way he was treated. While Turing was dealt with under the law of the time and we can't put the clock back, his treatment was of course utterly unfair and I am pleased to have the chance to say how deeply sorry I and we all are for what happened to him ... So on behalf of the British government, and all those who live freely thanks to Alan's work I am very proud to say: we're sorry, you deserved so much better.

### Tributes by universities

A celebration of Turing's life and achievements arranged by the British Logic Colloquium and the British Society for the History of Mathematicswas held on 5 June 2004.

- The 'Turing Room' at the University of Edinburgh's School of InformaticsUniversity of Edinburgh School of InformaticsThe School of Informatics is an academic unit of the University of Edinburgh, in Scotland, responsible for research, teaching, outreach and commercialisation in Informatics....

houses a bust of Turing by Eduardo PaolozziEduardo PaolozziSir Eduardo Luigi Paolozzi, KBE, RA , was a Scottish sculptor and artist. He was a major figure in the international art sphere, while, working on his own interpretation and vision of the world. Paolozzi investigated how we can fit into the modern world to resemble our fragmented civilization...

, and a set (#42/50) of his Turing prints (2000). - The University of SurreyUniversity of SurreyThe University of Surrey is a university located within the county town of Guildford, Surrey in the South East of England. It received its charter on 9 September 1966, and was previously situated near Battersea Park in south-west London. The institution was known as Battersea College of Technology...

has a statue of Turing on their main piazza. - Istanbul Bilgi UniversityIstanbul Bilgi UniversityIstanbul Bilgi University is a private, non-profit university in Istanbul, Turkey. It was actually established in 1994 under the name ISIS , but its name was changed to Istanbul Bilgi University with the foundation of the school on June 7, 1996...

organises an annual conference on the theory of computation called "Turing Days". - The University of Texas at AustinUniversity of Texas at AustinThe University of Texas at Austin is a state research university located in Austin, Texas, USA, and is the flagship institution of the The University of Texas System. Founded in 1883, its campus is located approximately from the Texas State Capitol in Austin...

has an honours computer science programme named the Turing Scholars. - In the early 1960s Stanford UniversityStanford UniversityThe Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

named the sole lecture room of the Polya Hall Mathematics building "Alan Turing Auditorium". - One of the amphitheatres of the Computer Science department (LIFLLaboratoire d'Informatique Fondamentale de LilleThe Laboratoire d'Informatique Fondamentale de Lille , is a computer science research laboratory of Lille University of Science and Technology , in Lille, France...

) at the University of LilleUniversity of LilleThe original university in the Lille region of France was the University of Douai established in 1559 in Douai and that was moved to Lille in 1887.University campuses in the Academy of Lille are members of the Université Lille Nord de France and European Doctoral College Lille Nord-Pas de...

in Northern France is named in honour of Alan M. Turing (the other amphitheatre is named after Kurt GödelKurt GödelKurt Friedrich Gödel was an Austrian logician, mathematician and philosopher. Later in his life he emigrated to the United States to escape the effects of World War II. One of the most significant logicians of all time, Gödel made an immense impact upon scientific and philosophical thinking in the...

). - The Department of Computer Science at Pontifical Catholic University of ChilePontifical Catholic University of ChileThe Pontifical Catholic University of Chile is one of the six Catholic Universities existing in the Chilean university system and one of the two Pontifical Universities in the country, along with the Pontifical Catholic University of Valparaíso. It is also one of Chile's oldest universities and...

, the Polytechnic University of Puerto RicoPolytechnic University of Puerto RicoThe Polytechnic University of Puerto Rico —commonly referred as Poly or La Poly in Spanish— is a private non-profit university located in San Juan, Puerto Rico...

, Los Andes UniversityUniversity of the Andes, ColombiaThe University of the Andes , is a coeducational, nonsectarian private university located in city centre Bogotá, Colombia. Founded in 1948, the University has 9 faculties: Administration, Architecture and Design, Arts and Humanities, Sciences, Social Sciences, Law, Economics, Engineering and...

in BogotáBogotáBogotá, Distrito Capital , from 1991 to 2000 called Santa Fé de Bogotá, is the capital, and largest city, of Colombia. It is also designated by the national constitution as the capital of the department of Cundinamarca, even though the city of Bogotá now comprises an independent Capital district...

, ColombiaColombiaColombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, King's College, CambridgeKing's College, CambridgeKing's College is a constituent college of the University of Cambridge, England. The college's full name is "The King's College of our Lady and Saint Nicholas in Cambridge", but it is usually referred to simply as "King's" within the University....

, Bangor UniversityBangor UniversityBangor University is a university based in the city of Bangor in the county of Gwynedd in North Wales-United Kingdom.It was officially known for most of its history as the University College of North Wales...

in WalesWalesWales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

and University of MonsUniversity of MonsThe University of Mons is a new Belgian university located in the city of Mons, created by merging the Engineering Faculty of Mons and the University of Mons-Hainaut...

in BelgiumBelgiumBelgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

have computer laboratories named after Turing. - The University of ManchesterUniversity of ManchesterThe University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...

, the Open UniversityOpen UniversityThe Open University is a distance learning and research university founded by Royal Charter in the United Kingdom...

, Oxford Brookes UniversityOxford Brookes UniversityOxford Brookes University is a new university in Oxford, England. It was named to honour the school's founding principal, John Brookes. It has been ranked as the best new university by the Sunday Times University Guide 10 years in a row...

and Aarhus University (in Århus, DenmarkDenmarkDenmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

) all have buildings named after Turing. - Alan Turing Road in the Surrey Research ParkSurrey Research ParkThe Surrey Research Park is located in Guildford, Surrey, UK close to the A3 road and the Royal Surrey County Hospital. The park is owned and run by the University of Surrey....

is named for Alan Turing. - Carnegie Mellon UniversityCarnegie Mellon UniversityCarnegie Mellon University is a private research university in Pittsburgh, Pennsylvania, United States....

has a granite bench, situated in the Hornbostel Mall, with the name "A. M. Turing" carved across the top, "Read" down the left leg, and "Write" down the other. - The École Internationale des Sciences du Traitement de l'Information has named its recently acquired third building "Turing".
- The University of Ghent has one of its main computer rooms (in a building used mostly by mathematicians and computing scientists) named after Alan Turing.
- The University of OregonUniversity of Oregon-Colleges and schools:The University of Oregon is organized into eight schools and colleges—six professional schools and colleges, an Arts and Sciences College and an Honors College.- School of Architecture and Allied Arts :...

has a bust of Turing on the side of the Deschutes Hall, the computer science building.

### Centenary commemoration

To mark the 100th anniversary of Turing's birth, the Turing Centenary Advisory Committee (TCAC) is coordinating the Alan Turing Year, a year-long programme of events around the world honouring Turing's life and achievements. The TCAC working with the University of Manchester

faculty members and a broad spectrum of people from Cambridge University and Bletchley Park

, is chaired by S. Barry Cooper

, with Alan Turing's nephew Sir John Dermot Turing acting as TCAC Honorary President.

Events are scheduled in many countries around the world including the USA, Brazil, China, Czech Republic, the Philippines

, New Zealand, Israel

, Spain, Norway

, Italy, Portugal

and Germany. The keystone events will be a three-day conference in Manchester, UK in June examining Turing's mathematical and code-breaking achievements, and a Turing Centenary Conference in Cambridge organised by King's College, Cambridge

and the association Computability in Europe

.

## See also

- Good–Turing frequency estimation
- Turing degreeTuring degreeIn computer science and mathematical logic the Turing degree or degree of unsolvability of a set of natural numbers measures the level of algorithmic unsolvability of the set...
- Turing machine examplesTuring machine examples-Turing's very first example:The following table is Turing's very first example :With regard to what actions the machine actually does, Turing states the following:...
- Turing switchTuring switchThe Turing switch is a logical construction similar to the Turing machine. The Turing switch models the operation of a basic network switch in a network of switches, much the same as a Turing machine models the operation of a basic computational entity. Both are named in honor of the English...
- Unorganized machine

## Further reading

- Gleick, James,
*The Information: A History, A Theory, A Flood*, New York: Pantheon, 2011, ISBN 9780375423727The Information: A History, a Theory, a FloodThe Information: A History, a Theory, a Flood is a book by science history writer James Gleick, author of Chaos: Making a New Science. It covers the genesis of our current information age. The Information has also been published in ebook formats by Fourth Estate and Random House, and as an... - Leavitt, David,
*The Man Who Knew Too Much: Alan Turing and the Invention of the Computer*, W. W. Norton, 2006

## External links

- Alan Turing RKBExplorer
- Alan Turing Year
- CiE 2012: Turing Centenary Conference
- Visual Turing
- Turing Machine calculators at Wolfram AlphaWolfram AlphaWolfram Alpha is an answer-engine developed by Wolfram Research. It is an online service that answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that might contain the answer as a search engine might...
- Alan Turing site maintained by Andrew HodgesAndrew HodgesAndrew Hodges is a mathematician, an author and a pioneer of the gay liberation movement of the 1970s.For the past decades , Hodges has focused his research activities on the twistor theory — the new approach to the problems of fundamental physics pioneered by the mathematician Roger...

including a short biography - AlanTuring.net – Turing Archive for the History of Computing by Jack CopelandJack CopelandBrian Jack Copeland is Professor of Philosophy at the University of Canterbury, Christchurch, New Zealand.Copeland received a BPhil and DPhil from the University of Oxford in philosophy, where he undertook research on modal and non-classical logic.He is the Director of the Turing Archive for the...
- The Turing Archive – contains scans of some unpublished documents and material from the Kings College, Cambridge archive
- Sherborne School Archives – holds papers relating to Alan Turing's time at Sherborne School
- Alan Turing plaques recorded on openplaques.org

### Papers

- An extensive list of Turing's papers, reports and lectures, plus translated versions and collections BibNetWiki
- Oral history interview with Donald W. Davies, Charles Babbage InstituteCharles Babbage InstituteThe Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....

, University of Minnesota; Davies describes computer projects at the U.K. National Physical Laboratory, from the 1947 design work of Alan Turing to the development of the two ACE computers - Oral history interview with Nicholas C. Metropolis, Charles Babbage InstituteCharles Babbage InstituteThe Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....

, University of Minnesota. Metropolis was the first director of computing services at Los Alamos National LaboratoryLos Alamos National LaboratoryLos Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

; topics include the relationship between Alan Turing and John von NeumannJohn von NeumannJohn von Neumann was a Hungarian-American mathematician and polymath who made major contributions to a vast number of fields, including set theory, functional analysis, quantum mechanics, ergodic theory, geometry, fluid dynamics, economics and game theory, computer science, numerical analysis,...