# Turing machine

Turing machine
/toor"ing, tyoor"-/, Math.
a hypothetical device with a set of logical rules of computation: the concept is used in mathematical studies of the computability of numbers and in the mathematical theories of automata and computers.
[after Alan M. Turing (1912-54), English mathematician, who described such a machine in 1936]

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Hypothetical computing device proposed by Alan M. Turing (1936).

Not actually a machine, it is an idealized mathematical model that reduces the logical structure of any computing device to its essentials. It consists of an infinitely extensible tape, a tape head that is capable of performing various operations on the tape, and a modifiable control mechanism in the head that can store instructions. As envisaged by Turing, it performs its functions in a sequence of discrete steps. His extrapolation of the essential features of information processing was instrumental in the development of modern digital computers, which share his basic scheme of an input/output device (tape and tape reader), central processing unit (CPU, or control mechanism), and stored memory.

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▪ computing device
hypothetical computing device introduced in 1936 by the English mathematician and logician Alan M. Turing (Turing, Alan M.). Turing originally conceived the machine as a mathematical tool that could infallibly recognize undecidable propositions—i.e., those mathematical statements that, within a given formal axiom system, cannot be shown to be either true or false. (The mathematician Kurt Gödel had demonstrated that such undecidable propositions exist in any system powerful enough to contain arithmetic.) Turing instead proved that there can never exist any universal algorithmic method for determining whether a proposition is undecidable.

The Turing machine is not a machine in the ordinary sense but rather an idealized mathematical model that reduces the logical structure of any computing device to its essentials. As envisaged by Turing, the machine performs its functions in a sequence of discrete steps and assumes only one of a finite list of internal states at any given moment. The machine itself consists of an infinitely extensible tape, a tape head that is capable of performing various operations on the tape, and a modifiable control mechanism in the head that can store directions from a finite set of instructions. The tape is divided into squares, each of which is either blank or has printed on it one of a finite number of symbols. The tape head has the ability to move to, read, write, and erase any single square and can also change to another internal state at any moment. Any such act is determined by the internal state of the machine and the condition of the scanned square at a given moment. The output of the machine—i.e., the solution to a mathematical query—can be read from the system once the machine has stopped. (However, in the case of Gödel's undecidable propositions, the machine would never stop, and this became known as the “halting problem.”)

By incorporating all the essential features of information processing, the Turing machine became the basis for all subsequent digital computers (digital computer), which share the machine's basic scheme of an input/output device (tape and reader), memory (control mechanism's storage), and central processing unit (control mechanism).

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Universalium. 2010.

### См. также в других словарях:

• Turing machine — Turing o mašina statusas T sritis automatika atitikmenys: angl. Turing machine vok. Turing Maschine, f rus. машина Тьюринга, f pranc. machine de Turing, f ryšiai: sinonimas – Tiuringo mašina …   Automatikos terminų žodynas

• Turing machine — 1937, named for English mathematician and computer pioneer Alan M. Turing (1912 1954), who described such a device in 1936 …   Etymology dictionary

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• Turing machine — noun An abstract computing machine introduced in 1936 by Alan Turing to give a mathematically precise definition of computability. See Also: universal Turing machine, Turing complete, Turing function …   Wiktionary

• Turing machine — Tu′ring machine [[t]ˈtʊər ɪŋ, ˈtyʊər [/t]] n. math. a hypothetical computing device used in mathematical studies of the computability of numbers and in theories of automata • Etymology: after Alan M. Turing (1912–54), English mathematician, who… …   From formal English to slang

• Turing machine — noun Etymology: A. M. Turing died 1954 English mathematician Date: 1937 a hypothetical computing machine that has an unlimited amount of information storage …   New Collegiate Dictionary

• Turing machine — noun a mathematical model of a hypothetical computing machine which can use a predefined set of rules to determine a result from a set of input variables. Origin named after the English mathematician Alan Turing (1912–54) …   English new terms dictionary

• Turing machine — /ˈtjurɪŋ məˌʃin/ (say tyoohring muh.sheen) noun a postulated basic computing device consisting of a tape, a scanner, a printer and a table of states in vector form (I,O,N,D), where I is the symbol scanned, O the symbol output, N the next state, D …   Australian English dictionary

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