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What's This?Alan Mathison Turing, OBE, FRS (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

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In a letter written to his friend Norman Routledge near the end of his life, Turing linked his arrest with his accomplishments in an extraordinary syllogism:

Turing believes machines think,

Turing lies with men,

Therefore machines cannot think

In 1939-40 Alan Turing and another Cambridge mathematician, Gordon Welchman, designed a new machine, the British Bombe. The basic property of the Bombe was that it could break any Enigma-enciphered message, provided that the hardware of the Enigma was known and that a plain-text 'crib' of about 20 letters could be guessed accurately.

In the 1940s Turing designed what are considered the first operational electronic digital computers.

The Turing test is really nothing more than a clever adaptation of a party game. The test has three participants. One of them, the interrogator, is placed in a separate room from the other two, one a male and the other female. Questions and responses are typed and passed under the door. The goal of the game is for the interrogator to determine through the line of questioning which of the interviewees is the male and which is the female. To further complicate the situation, the male is supposed to attempt to throw off the hunt while the female is supposed to aid the interrogator. Turing reasoned the role of the male could very well be played by a computer, and if the interrogator, a human, could not tell the which of the two interviewees was man or machine, the computer could be considered intelligent. The Turing test is considered Alan Turing's single greatest accomplishment in the realm of artificial intelligence, and, to date, no machine has been able to pass the test.

In 1952, Turing was arrested and tried for homosexuality, then a criminal offence. To avoid prison, he accepted injections of oestrogen for a year, which were intended to neutralise his libido. In that era, homosexuals were considered a security risk as they were open to blackmail. Turing's security clearance was withdrawn, meaning he could no longer work for GCHQ, the post-war successor to Bletchley Park.

In 1954 he was found dead in his bed, a half eaten apple on the table beside him, according to legend laced with the cyanide which killed him.

His mother insisted that his death was accidental, part of an experiment to silver plate a spoon...

Throughout his life he was misunderstood, ignored, even ridiculed. His manners were gross; his appearance verged on the disreputable. In attempting to explain to colleagues the visionary ideas crammed into his giant intellect, he often relapsed into almost incomprehensible stammering. He was mysterious and contradictory, but in a short life span - only 42 years - his discoveries and inventions saved thousands of lives. Yet, he was unknown in life and almost anonymous in death.

Alan Mathison Turing was born on 23 June 1912 in London; he died on 7 june 1954 at his home in Wilmslow, Cheshire. Turing contributed to logic, mathematics, biology, philosophy, cryptanalysis, and formatively to the areas later known as computer science, cognitive science, Artificial Intelligence, and Artificial Life.

...Alan Turing's early life was marked by detachment from the obligatory social training... It was also marked from the start by his intensely individual response to science and mathematics, in particular to the relativity and quantum mechanics which had transformed the physical sciences since 1900. He became an undergraduate at King's College, Cambridge University, in 1931, reading mathematics and graduating with distinction in 1934.

Online search engines, which work with such astonishing speed and power, are algorithms, and so equivalent to Turing machines. They are also descendants of the particular algorithms, using sophisticated logic, statistics and parallel processing, that Turing expertly pioneered for Enigma-breaking. These were search engines for the keys to the Reich.

It turns out that every logical procedure, every algorithm, every mathematical proof, every computer program can be realized as a Turing machine. The Turing machine is a "universal logical device". ... In effect, Turing had designed a computer before technology had made it possible to actually build one.

A Turing machine is an abstract conceptual model. It consists of a scanner and a limitless memory-tape. The tape is divided into squares, each of which may be blank or may bear a single symbol...The scanner moves back and forth through the memory, examining one square at a time... It reads the symbols on the tape and writes further symbols. The tape is both the memory and the vehicle for input and output.