# A. M. Turing

**Alan Mathison Turing**, OBE, FRS (23 June 1912 – 7 June 1954) was an English mathematician, logician, and cryptographer.

Turing is often considered to be the father of modern computer science. Turing provided an influential formalisation of the concept of the algorithm and computation with the Turing machine, formulating the now widely accepted "Turing" version of the Church–Turing thesis, namely that any practical computing model has either the equivalent or a subset of the capabilities of a Turing machine. With the Turing test, he made a significant and characteristically provocative contribution to the debate regarding artificial intelligence: whether it will ever be possible to say that a machine is conscious and can think. He later worked at the National Physical Laboratory, creating one of the first designs for a stored-program computer, although it was never actually built. In 1948 he moved to the University of Manchester to work on the Manchester Mark I, then emerging as one of the world's earliest true computers.

During the Second World War Turing worked at Bletchley Park, Britain's codebreaking centre, and was for a time head of Hut 8, the section responsible for German naval cryptanalysis. He devised a number of techniques for breaking German ciphers, including the method of the bombe, an electromechanical machine that could find settings for the Enigma machine.

In 1952, Turing was convicted of "acts of gross indecency" after admitting to a sexual relationship with a man in Manchester. He was placed on probation and required to undergo estrogen therapy to achieve temporary chemical castration.<ref name="hodges1983" /> Turing died after eating an apple laced with cyanide in 1954. His death was ruled a suicide.

## Childhood and youth

Turing was conceived in 1911 in Chhatrapur, Orissa, India.^{[1]}His father, Julius Mathison Turing, was a member of the Indian Civil Service. Julius and wife Sara (

*née*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,

^{[2]}London, where Alan Turing was born 23 June 1912, as recorded by a blue plaque on the outside of the building, now the Colonnade Hotel.

^{[3]}

^{[4]}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 Guildford, England and India, leaving their two sons to stay with friends in England. Very early in life, Turing showed signs of the genius he was to display more prominently later.

^{[5]}

His parents enrolled him at St Michael's, a day school, at the age of six. The headmistress recognised his genius early on, as did many of his subsequent educators. In 1926, at the age of 14, he went on to Sherborne School in Dorset. His first day of term coincided with General Strike in England, but so determined was he to attend his first day that he rode his bike unaccompanied more than 60 miles from Southampton to school, stopping overnight at an inn.

^{[6]}

Turing's natural inclination toward mathematics and science did not earn him respect with the teachers at Sherborne, a famous and expensive public school, whose definition of education placed more emphasis on the classics. His headmaster wrote to his parents: "I hope he will not fall between two schools. 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".

^{[7]}

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.

^{[8]}

Turing's hopes and ambitions at school were raised by his strong feelings for his best friend Christopher Morcom, with whom he fell in love, though the feeling was not reciprocated. Morcom died suddenly 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.

^{[9]}

## University and his work on computability

Turing's unwillingness to work as hard on his classical studies as on science and mathematics meant he failed to win a scholarship to Trinity College, Cambridge, and went on to the college of his second choice, King's College, Cambridge. He was an undergraduate there from 1931 to 1934, graduating with a distinguished degree, and in 1935 was elected a fellow at King's on the strength of a dissertation on the central limit theorem.In his momentous paper "On Computable Numbers, with an Application to the

*Entscheidungsproblem*" (submitted on 28 May 1936), Turing reformulated Kurt Gödel's 1931 results on the limits of proof and computation, replacing Gödel's universal arithmetic-based formal language with what are now called Turing machines, formal and simple devices. He proved that such a machine would be capable of performing any conceivable mathematical problem if it were representable as an algorithm, even if no actual Turing machine would be likely to have practical applications, being much slower than alternatives.

Turing machines are to this day the central object of study in theory of computation. 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's work 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. The paper also introduces the notion of definable numbers.

Most of 1937 and 1938 he spent at Princeton University, studying under Alonzo Church. In 1938 he obtained his Ph.D. from Princeton; his dissertation introduced 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 in 1939, he attended lectures by Ludwig Wittgenstein about the foundations of mathematics.

^{[10]}The two argued and disagreed, with Turing defending formalism and Wittgenstein arguing that mathematics is overvalued and does not discover any absolute truths.

^{[11]}

## Cryptanalysis

During the Second World War, Turing was a main participant in the efforts at Bletchley Park to break German ciphers. Building on cryptanalysis work carried out in Poland before the war, he contributed several insights into breaking both the Enigma machine and the Lorenz SZ 40/42 (a teletype cipher attachment codenamed "Tunny" by the British), and was, for a time, head of Hut 8, the section responsible for reading German naval signals.Since September 1938, Turing had been working part-time for the Government Code and Cypher School (GCCS), the British codebreaking organisation. He worked on the problem of the German Enigma machine, and collaborated with Dilly Knox, a senior GCCS codebreaker.

^{[12]}On 4 September 1939, the day after Britain declared war on Germany, Turing reported to Bletchley Park, the wartime station of GCCS.

^{[13]}

### The Turing-Welchman bombe

Within weeks of arriving at Bletchley Park,<ref name="copeland2006" /> Turing had designed an electromechanical machine which could help break Enigma: the bombe, named after and building upon the original Polish-designed*bomba*. They were also referred to as “Bronze Goddesses” because their cases were made of bronze, but they were more prosaically described by operators as being “like great big metal bookcases”.

^{[14]}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.

Professor Jack Good, cryptanalyst working at the time with Turing at Bletchley Park, later said: "Turing's most important contribution, I

*think*, 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 deduce

*everything.*"

^{[15]}

The bombe searched for possibly correct settings used for an Enigma message (ie, 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 U-Boat Enigmas which eventually had four rotors, compared to the usual Enigma variant's three

^{[16]}), 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.

^{[17]}Over 200 bombes were in operation by the end of the war.

^{[18]}

### Hut 8 and Naval Enigma

In December 1940, Turing solved the naval Enigma indicator system, which was more complex than the indicator systems used by the other services. Turing also invented a Bayesian statistical technique termed "Banburismus" to assist in breaking Naval Enigma. Banburismus could rule out certain orders of the Enigma rotors, reducing time needed to test settings on the bombes.In the spring of 1941, Turing proposed marriage to Hut 8 co-worker Joan Clarke, although the engagement was broken off by mutual agreement in the summer.

In July 1942, Turing devised a technique termed

*Turingismus*or

*Turingery*for use against the Lorenz cipher used in the Germans' new Geheimschreiber machine ("secret writer") which was one of those codenamed "Fish". He also introduced the Fish 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 simpler prior machine (including the "Heath Robinson") and whose superior speed allowed the brute-force decryption techniques to be applied usefully to the daily-changing cyphers.

^{[19]}A frequent misconception is that Turing was a key figure in the design of Colossus; this was not the case.

^{[20]}

Turing travelled to the United States in November 1942 and worked with US 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.

In the latter part of the war, while teaching himself electronics at the same time, and assisted by engineer Donald Bayley, Turing undertook the design of a portable machine codenamed

*Delilah*to allow secure voice communications. 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.

In 1945, Turing was awarded the OBE for his wartime services, but his work remained secret for many years. A biography published by the Royal Society shortly after his death 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."
^{[21]}

## Early computers and the Turing Test

From 1945 to 1947 he was at the National Physical Laboratory, where he worked on the design of the ACE (Automatic Computing Engine). He presented a paper on 19 February 1946, which was the first complete design of a stored-program computer in Britain. Although he succeeded in designing the ACE, there were 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, ACE was completed in his absence and executed its first program on 10 May 1950. In 1948 he was appointed Reader in the Mathematics Department at Manchester and in 1949 became deputy director of the computing laboratory at the University of Manchester, and worked on software for one of the earliest true computers — the Manchester Mark I. 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 now known as the Turing test, an attempt to define a standard for a machine to be called "sentient".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.

## 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 Morphogenesis" in 1952, putting forth the Turing hypothesis of pattern formation.^{[1]}His central interest in the field was understanding Fibonacci phyllotaxis, the existence of Fibonacci numbers in plant structures. He used reaction-diffusion equations which are now central to the field of pattern formation. Later papers went unpublished until 1992 when

*Collected Works of A.M. Turing*was published.

## Prosecution for homosexual acts and Turing's death

Turing was homosexual<ref name="hodges1983" /> in a period when homosexual acts were illegal in Britain and homosexuality was regarded as a mental illness and subject to criminal sanctions. In 1952, Arnold Murray, a 19-year-old recent acquaintance of his,^{[22]}helped an accomplice to break into Turing's house, and Turing went to the police to report the crime. As a result of the police investigation, Turing acknowledged a sexual relationship with Murray, and a crime having been identified and settled, they were charged with gross indecency under Section 11 of the Criminal Law Amendment Act of 1885. Turing was unrepentant and was convicted. He was given the choice between imprisonment and probation, conditional on his undergoing hormonal treatment designed to reduce libido. In order to avoid going to jail, he accepted the oestrogen hormone injections, which lasted for a year, with side effects including gynecomastia (breast enlargement). His conviction led to a removal of his security clearance and prevented him from continuing consultancy for GCHQ on cryptographic matters.

On 8 June 1954, his cleaner found him dead; the previous day, he had died of cyanide poisoning, apparently from a cyanide-laced apple he left half-eaten beside his bed. The apple itself was never tested for contamination with cyanide, and cyanide poisoning as a cause of death was established by a post-mortem. Most believe that his death was intentional, and the death was ruled a suicide. His mother, however, strenuously argued that the ingestion was accidental due to his careless storage of laboratory chemicals. Biographer Andrew Hodges suggests that Turing may have killed himself in this ambiguous way quite deliberately, to give his mother some plausible deniability.

^{[23]}Others suggest that Turing was reenacting a scene from "Snow White", his favourite fairy tale.

^{[24]}Because Turing's homosexuality would have been perceived as a security risk, the possibility of assassination has also been suggested.

^{[25]}His remains were cremated at Woking crematorium on 12 June 1954.

It has been claimed that the Apple Computer logo (an apple with a bite taken out) may be a coded tribute to Alan Turing.

^{[26]}Turing's biographer, Andrew Hodges, has asserted that this is false.

^{[27]}

## Posthumous recognition

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 equivalent to the Nobel Prize.Various tributes to Turing have been made in Manchester, the city where he worked towards the end of his life. In 1994 a stretch of the Manchester city inner ring road was named Alan Turing Way. 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'. A celebration of Turing's life and achievements arranged by the British Logic Colloquium and the British Society for the History of Mathematics was held on 5 June 2004 at the University of Manchester and the Alan Turing Institute was initiated in the university that summer. The building housing the School of Mathematics, the Photon Sciences Institute, and the Jodrell Bank Centre for Astrophysics is named the

*Alan Turing Building*and was opened in July 2007.

On 23 June 1998, on what would have been Turing's 86th birthday, Andrew Hodges, his biographer, unveiled an official English Heritage Blue Plaque on his childhood home in Warrington Crescent, London, now the Colonnade hotel.

^{[28]}

^{[29]}To mark the 50th anniversary of his death, a memorial plaque was unveiled on 7 June 2004 at his former residence, Hollymeade, in Wilmslow.

For his achievements in computing, various universities have honoured him. On 28 October 2004 a bronze statue of Alan Turing sculpted by John W Mills was unveiled at the University of Surrey.

^{[30]}The statue marks the 50th anniversary of Turing's death. It portrays Turing carrying his books across the campus. The Polytechnic University of Puerto Rico and Los Andes University of Bogotá, Colombia, both have computer laboratories named after Turing. The University of Texas at Austin has an honours computer science program named the Turing Scholars. Istanbul Bilgi University organizes an annual conference on the theory of computation called Turing Days.

^{[31]}Cambridge University has a computer lab in King's College, Cambridge named the "Turing Room". Carnegie Mellon University 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 Boston GLBT pride organization named Turing their 2006 Honorary Grand Marshal.

^{[32]}

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.

^{[33]}

The Turing Relay

^{[34]}is a six-stage relay race on riverside footpaths from Ely to Cambridge and back to Ely. These paths were used for running by Turing while at Cambridge; his marathon best time was 2 hours, 46 minutes.

## Turing in fiction

- Physicist Janna Levin's novel
*A Madman Dreams of Turing Machines*focuses on the lives of both Alan Turing and Kurt Gödel. - In the 1989
*Doctor Who*serial*The Curse of Fenric*, the character of Dr Judson is based on Turing. Turing himself is a narrator of the*Doctor Who*spin-off novel*The Turing Test*by Paul Leonard. An Alan Turing from a parallel universe appears in the later novel*The Domino Effect*by David Bishop. - Greg Egan's novella,
*Oracle*, is about an alternate universe version of Turing. - In William Gibson's seminal cyberpunk novel
*Neuromancer*, the sinister body tasked with the regulation and suppression of artificial intelligences is called the "Turing Registry", and its agents are referred to as the "Turing Police". - In 1987 German author and playwright Rolf Hochhuth published the novel
*Alan Turing*after reading the biography written by Turing's mother. - Neal Stephenson's novel Cryptonomicon features Turing as a supporting character.
- The protagonist of Robert Harris's novel
*Enigma*and the film made from it is arguably based upon Turing.

## Further reading

- Agar, Jon (2002).
*The Government Machine*. Cambridge, Massachusetts: The MIT Press. ISBN 0262012022 - Beniger, James (1986).
*The Control Revolution: Technological and Economic Origins of the Information Society*. Cambridge, Massachusetts: Harvard University Press. ISBN 0674169867 - Bodanis, David (2005).
*Electric Universe: How Electricity Switched on the Modern World*. New York: Three Rivers Press. ISBN 0-307-33598-4. - Campbell-Kelly, Martin (ed.) (1994).
*Passages in the Life of a Philosopher*. London: William Pickering. ISBN 0813520665 - Campbell-Kelly, Martin, and Aspray, William (1996).
*Computer: A History of the Information Machine*. New York: Basic Books. ISBN 0-465-02989-2 - Ceruzzi, Paul (1998).
*A History of Modern Computing*. Cambridge, Massachusetts, and London: MIT Press. ISBN 0-262-53169-0 - Chandler, Alfred (1977).
*The Visible Hand: The Managerial Revolution in American Business*. Cambridge, Massachusetts: Belknap Press. ISBN 0674940520 - Copeland, B. Jack (2004). "Colossus: Its Origins and Originators".
*IEEE Annals of the History of Computing***26**(4): 38 — 45. - Copeland, B. Jack (ed.) (2004).
*The Essential Turing*. Oxford: Oxford University Press. ISBN 0-19-825079-7. - Copeland (ed.), B. Jack (2005).
*Alan Turing's Automatic Computing Engine*. Oxford: Oxford University Press. ISBN 0-19-856593-3. - Edwards, Paul N (1996).
*The Closed World*. Cambridge, Massachusetts: MIT Press. ISBN 0262550288 - Hodges, Andrew (1983).
*Alan Turing: The Enigma of Intelligence*. London: Burnett Books. ISBN 0045100608 - Leavitt, David (2006) "The Man Who Knew Too Much - Alan Turing and the invention of the computer" Orion Books ltd ISBN 9780753822005
- Lubar, Steven (1993)
*Infoculture*. Boston and New York: Houghton Mifflin. ISBN 039557045 - O'Connor, John J; Edmund F. Robertson "Alan Mathison Turing".
*MacTutor History of Mathematics archive*. - Smith, Roger (1997).
*Fontana History of the Human Sciences*. London: Fontana. - Weizenbaum, Joseph (1976).
*Computer Power and Human Reason*. London: W.H. Freeman. ISBN 0716704633 - Williams, Michael R. (1985).
*A History of Computing Technology*. Englewood Cliffs, New Jersey: Prentice-Hall. ISBN 0-8186-7739-2 - Yates, David M. (1997).
*Turing's Legacy: A history of computing at the National Physical Laboratory 1945 – 1995*. London: London Science Museum. ISBN 0-901805-94-7.London&rft.isbn=0-901805-94-7"> - Turing's mother, Sara Turing, who survived him by many years, wrote a biography of her son glorifying his life. Published in 1959, it could not cover his war work; scarcely 300 copies were sold.
^{[35]}The six-page foreword by Lyn Irvine includes reminiscences and is more frequently quoted. *Breaking the Code*is a 1986 play by Hugh Whitemore, telling the story of Turing's life and death. In the original West End and Broadway runs, Derek Jacobi played Turing – and he recreated the role in a 1997 television film based on the play made jointly by the BBC and WGBH, Boston.The play is published by Amber Lane Press, Oxford. ASIN: B000B7TM0Q

## See also

## References

1. ^ Hodges, 1983, p. 5

2. ^ London Blue Plaques.

3. ^ Hodges, Andrew (1983).

4. ^ The Alan Turing Internet Scrapbook. Retrieved on 2006-09-26.

5. ^ Jones, G. James (2001-12-11). Alan Turing - Towards a Digital Mind: Part 1.

6. ^ Hofstadter, Douglas R. (1985).

7. ^ Hodges, 1983, p. 26

8. ^ Hodges, 1983, p. 34

9. ^ ** Teuscher, Christof (ed.) (2004).

10. ^ Hodges, 1983, p. 152

11. ^ Hodges, 1983, pp. 153-154

12. ^ Jack Copeland, "Colossus and the Dawning of the Computer Age", p. 352 in

13. ^ Copeland (ed.), B. Jack (2006).

14. ^ Mary Stewart, 'Bombe' Operator, interviewed in "The Men Who Cracked Enigma", UKTV History Channel documentary series "Heroes of World War II", 2003

15. ^ "The Men Who Cracked Enigma", 2003

16. ^ Professor Jack Good in "The Men Who Cracked Enigma", 2003: with his caveat: "if my memory is correct"

17. ^ Hodges, 1983, p. 191

18. ^ Copeland, Jack; Diane Proudfoot (May, 2004). Alan Turing, Codebreaker and Computer Pioneer. Retrieved on 2007-07-27.

19. ^ Copeland, 2006, pp. 72

20. ^ Copeland, 2006, pp. 382-383

21. ^ Newman, M. H. A. (1955).

22. ^ cf. Hodges, pp.449-455

23. ^ Hodges, 1983, pp. 488-489

24. ^ Ferris, Timothy.

25. ^ Leavitt, David (2006).

26. ^ "Alan Turing" The Times Online, January 25, 2005[2]

27. ^ Andrew Hodges, "Wondrous Light: 1952-1954", The Alan Turing Internet Scrapbook, last updated September 2003, last accessed August 2007

28. ^ Unveiling the official Blue Plaque on Alan Turing's Birthplace. Retrieved on 2006-09-26.

29. ^ About this Plaque - Alan Turing. Retrieved on 2006-09-25.

30. ^ The Earl of Wessex unveils statue of Alan Turing. Retrieved on 2007-02-10.

31. ^ Turing Days @ İstanbul Bilgi University. Retrieved on 2007-02-10.

32. ^ Honorary Grand Marshal. Retrieved on 2007-02-10.

33. ^ Bletchley Park Unveils Statue Commemorating Alan Turing, Bletchley Park press release, 20 June 2007]

34. ^ Turing Trail Relay

35. ^ Sara Turing to Lyn Newman, 1967, Library of St John's College, Cambridge.

2. ^ London Blue Plaques.

*English-Heritage.org.uk*. Retrieved on 2007-02-10.3. ^ Hodges, Andrew (1983).

*Alan Turing: The Enigma*. New York: Simon & Schuster, pp. 5. ISBN 0-671-49207-1.4. ^ The Alan Turing Internet Scrapbook. Retrieved on 2006-09-26.

5. ^ Jones, G. James (2001-12-11). Alan Turing - Towards a Digital Mind: Part 1.

*System Toolbox*. Retrieved on 2007-07-27.6. ^ Hofstadter, Douglas R. (1985).

*Metamagical Themas: Questing for the Essence of Mind and Pattern*. Basic Books. ISBN 0465045669.7. ^ Hodges, 1983, p. 26

8. ^ Hodges, 1983, p. 34

9. ^ ** Teuscher, Christof (ed.) (2004).

*Alan Turing: Life and Legacy of a Great Thinker*. Springer-Verlag. ISBN 3-540-20020-7.10. ^ Hodges, 1983, p. 152

11. ^ Hodges, 1983, pp. 153-154

12. ^ Jack Copeland, "Colossus and the Dawning of the Computer Age", p. 352 in

*Action This Day*, 200113. ^ Copeland (ed.), B. Jack (2006).

*Colossus: The Secrets of Bletchley Park's Codebreaking Computers*. New York: Oxford University Press, p. 378. ISBN 019284055X.14. ^ Mary Stewart, 'Bombe' Operator, interviewed in "The Men Who Cracked Enigma", UKTV History Channel documentary series "Heroes of World War II", 2003

15. ^ "The Men Who Cracked Enigma", 2003

16. ^ Professor Jack Good in "The Men Who Cracked Enigma", 2003: with his caveat: "if my memory is correct"

17. ^ Hodges, 1983, p. 191

18. ^ Copeland, Jack; Diane Proudfoot (May, 2004). Alan Turing, Codebreaker and Computer Pioneer. Retrieved on 2007-07-27.

19. ^ Copeland, 2006, pp. 72

20. ^ Copeland, 2006, pp. 382-383

21. ^ Newman, M. H. A. (1955).

*Alan Mathison Turing*, Biographical Memoirs of Fellows of the Royal Society, 1955, Volume 1. The Royal Society.22. ^ cf. Hodges, pp.449-455

23. ^ Hodges, 1983, pp. 488-489

24. ^ Ferris, Timothy.

*Seeing in the Dark*. 2002. p. 25025. ^ Leavitt, David (2006).

*The man who knew too much: Alan Turing and the invention of the computer*. New York: W. W. Norton. ISBN 0393052362.26. ^ "Alan Turing" The Times Online, January 25, 2005[2]

27. ^ Andrew Hodges, "Wondrous Light: 1952-1954", The Alan Turing Internet Scrapbook, last updated September 2003, last accessed August 2007

28. ^ Unveiling the official Blue Plaque on Alan Turing's Birthplace. Retrieved on 2006-09-26.

29. ^ About this Plaque - Alan Turing. Retrieved on 2006-09-25.

30. ^ The Earl of Wessex unveils statue of Alan Turing. Retrieved on 2007-02-10.

31. ^ Turing Days @ İstanbul Bilgi University. Retrieved on 2007-02-10.

32. ^ Honorary Grand Marshal. Retrieved on 2007-02-10.

33. ^ Bletchley Park Unveils Statue Commemorating Alan Turing, Bletchley Park press release, 20 June 2007]

34. ^ Turing Trail Relay

35. ^ Sara Turing to Lyn Newman, 1967, Library of St John's College, Cambridge.

## External links

- O'Connor, John J; Edmund F. Robertson "Alan Turing".
*MacTutor History of Mathematics archive*. - Alan Turing site maintained by Andrew Hodges including a short biography
- AlanTuring.net Turing Archive for the History of Computing by Jack Copeland
- The Turing Archive - contains scans of some unpublished documents and material from the Kings College archive
- Alan Turing — Towards a Digital Mind: Part 1
- Time 100:Alan Turing
- Stanford Encyclopedia of Philosophy entry
- Alan Mathison Turing Memorial at Find A Grave

### Papers

- "Computing machinery and intelligence"
- Turing's paper titled "On Computable Numbers with an Application to the Entscheidungsproblem" (PDF)

Persondata | |
---|---|

NAME | Turing, Alan Mathison |

ALTERNATIVE NAMES | |

SHORT DESCRIPTION | Computer scientist, mathematician, and cryptographer |

DATE OF BIRTH | May 23 1912 |

PLACE OF BIRTH | Paddington, London, England |

DATE OF DEATH | May 7 1954 |

PLACE OF DEATH | Manchester, England |

**The Most Excellent Order of the British Empire**is a British order of chivalry established on 4 June 1917 by King George V. The Order includes five classes in civil and military divisions; in decreasing order of seniority, these are:

**Knight Grand Cross**or

**.....**Click the link for more information.

**Fellow of the Royal Society**is an honour accorded to distinguished scientists and a category of membership of the Royal Society. Fellows are entitled to put the letters

**FRS**after their name.

Up to 44 new fellows are elected each year by ballot of the existing fellows.

**.....**Click the link for more information.

June 23 is the 1st day of the year (2nd in leap years) in the Gregorian calendar. There are 0 days remaining.

## Events

- 1305 - Flemish-French peace treaty signed at Athis-sur-Orge.

**.....**Click the link for more information. 19th century -

1880s 1890s 1900s - 1910s - 1920s 1930s 1940s

1909 1910 1911 -

Year

**20th century**- 21st century1880s 1890s 1900s - 1910s - 1920s 1930s 1940s

1909 1910 1911 -

**1912**- 1913 1914 1915Year

**1912**(**MCMXII****.....**Click the link for more information. June 7 is the 1st day of the year (2nd in leap years) in the Gregorian calendar. There are 0 days remaining.

In common years it is always in ISO week 23.

In common years it is always in ISO week 23.

**.....**Click the link for more information. 19th century -

1920s 1930s 1940s - 1950s - 1960s 1970s 1980s

1951 1952 1953 -

Year

**20th century**- 21st century1920s 1930s 1940s - 1950s - 1960s 1970s 1980s

1951 1952 1953 -

**1954**- 1955 1956 1957Year

**1954**(**MCMLIV****.....**Click the link for more information.**Motto**

*Dieu et mon droit*(French)

"God and my right"

**Anthem**

No official anthem specific to England — the anthem of the United Kingdom is "God Save the Queen".

**.....**Click the link for more information.

**mathematician**is a person whose primary area of study and research is the field of mathematics.

## Problems in mathematics

Some people incorrectly believe that mathematics has been fully understood, but the publication of new discoveries in mathematics continues at an immense**.....**Click the link for more information.

**Logic**(from Classical Greek λόγος logos; meaning word, thought, idea, argument, account, reason, or principle) is the study of the principles and criteria of valid inference and demonstration.

**.....**Click the link for more information.

**Cryptography**(or cryptology; derived from Greek κρυπτός

*kryptós*"hidden," and the verb γράφω

*gráfo*"write" or λεγειν

*legein*

**.....**Click the link for more information.

**Computer science**, or

**computing science**, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems.

**.....**Click the link for more information.

In mathematics, computing, linguistics, and related disciplines, an

**algorithm**is a finite list of well-defined instructions for accomplishing some task that, given an initial state, will proceed through a well-defined series of successive states, eventually terminating in an**.....**Click the link for more information.**Turing machines**are extremely basic abstract symbol-manipulating devices which, despite their simplicity, can be adapted to simulate the logic of any computer that could possibly be constructed. They were described in 1936 by Alan Turing.

**.....**Click the link for more information.

**Turing test**is a proposal for a test of a machine's capability to demonstrate intelligence. Described by Professor Alan Turing in the 1950 paper "Computing machinery and intelligence," it proceeds as follows: a human judge engages in a natural language conversation with one human

**.....**Click the link for more information.

**artificial intelligence**(or

**AI**) is "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions which maximizes its chances of success.

**.....**Click the link for more information.

**Consciousness**is a characteristic of the mind generally regarded to comprise qualities such as subjectivity, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment.

**.....**Click the link for more information.

**Thought**or

**thinking**is a mental process which allows beings to model the world, and so to deal with it effectively according to their goals, plans, ends and desires.

**.....**Click the link for more information.

The

**National Physical Laboratory**(NPL) is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington in the London Borough of Richmond upon Thames.**.....**Click the link for more information.**Victoria University of Manchester**(more commonly known simply as the

**University of Manchester**) was a university in Manchester in England. On October 1 2004 it merged with the University of Manchester Institute of Science and Technology to form a new institution called the

**.....**Click the link for more information.

**Manchester Mark I**was one of the earliest electronic computers, built at the University of Manchester in England, in 1949. It was also called

**Manchester Automatic Digital Machine**, or

**MADM**. It was developed from the Small-Scale Experimental Machine (SSEM) or "Baby".

**.....**Click the link for more information.

**Allied powers**:

Soviet Union

United States

United Kingdom

China

France

...

*et al*.

**Axis powers**:

Germany

Japan

Italy

...

*et al*.

**.....**Click the link for more information.

**Bletchley Park**, also known as

**Station X**, is an estate located in the town of Bletchley, in Buckinghamshire now part of Milton Keynes, England. During World War II, Bletchley Park was the location of the United Kingdom's main codebreaking establishment.

**.....**Click the link for more information.

**Cryptanalysis**(from the Greek

*kryptós*, "hidden", and

*analıein*, "to loosen" or "to untie") is the study of methods for obtaining the meaning of encrypted information, without access to the secret information which is normally required to do so.

**.....**Click the link for more information.

**Hut 8**was a section at Bletchley Park (the British World War II codebreaking station) tasked with solving German naval Enigma messages. The section was led initially by Alan Turing. He was succeeded by his deputy Conel Hugh O'Donel Alexander in November 1942.

**.....**Click the link for more information.

**Anthem**

"

*Das Lied der Deutschen*" (third stanza)

also called "

*Einigkeit und Recht und Freiheit*"

**.....**Click the link for more information.

**Enigma cipher machine**

- Enigma machine
- Enigma rotor details
- Cryptanalysis of the Enigma
- Cyclometer

**.....**Click the link for more information.

**Enigma cipher machine**

- Enigma machine
- Enigma rotor details
- Cryptanalysis of the Enigma
- Cyclometer

**.....**Click the link for more information.

**Estrogens**(alternative spellings:

**oestrogens**or

**œstrogens**) are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone.

**.....**Click the link for more information.

**Chemical castration**is a form of temporary castration caused by certain hormonal drugs. It has been controversially used as a temporary preventive measure or punishment, typically for those who have broken laws of a sexual nature.

**.....**Click the link for more information.

**cyanide**ion, CN

^{−}.

From the top:

1. Valence-bond structure

2. Space-filling model

3. Electrostatic potential surface

4. 'Carbon lone pair' HOMO]] A

**cyanide**

**.....**Click the link for more information.

This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.