Alan Turing

Alan Turing was born in India but went to school at Sherborne .
 He got dreadful school reports but It was here that he read Einsteins Theory of Relativity and fell in love .

The picture shows them playing noughts and crosses in late 1929, and talking about mathematics and astronomy when they were meant to be doing French.

The figure on the right hand edge suggests that they were talking about the problem of the axiom of parallel lines in Euclidean geometry.

http://www.turing.org.uk
/scrapbook/spirit.html

the above is from a book about Turing - but look at the top left . Is he drawing the Great Bear ?

 
Images for "Turing Machine "
 

 
 

Turing machine   from Wikipedia

A Turing machine is a hypothetical device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a computer.

The "machine" was invented in 1936 by Alan Turing[1][2] who called it an "a-machine" (automatic machine). The Turing machine is not intended as practical computing technology, but rather as a hypothetical device representing a computing machine. Turing machines help computer scientists understand the limits of mechanical computation.

In his 1948 essay, "Intelligent Machinery", Turing wrote that his machine consisted of:

...an unlimited memory capacity obtained in the form of an infinite tape marked out into squares, on each of which a symbol could be printed. At any moment there is one symbol in the machine; it is called the scanned symbol. The machine can alter the scanned symbol and its behavior is in part determined by that symbol, but the symbols on the tape elsewhere do not affect the behavior of the machine. However, the tape can be moved back and forth through the machine, this being one of the elementary operations of the machine. Any symbol on the tape may therefore eventually have an innings.[3] ((Turing 1948, p. 3)

A Turing machine that is able to simulate any other Turing machine is called a universal Turing machine (UTM, or simply a universal machine). A more mathematically oriented definition with a similar "universal" nature was introduced by Alonzo Church, whose work on lambda calculus intertwined with Turing's in a formal theory of computation known as the Church–Turing thesis. The thesis states that Turing machines indeed capture the informal notion of effective methods in logic and mathematics, and provide a precise definition of an algorithm or "mechanical procedure". Studying their abstract properties yields many insights into computer science and complexity theory.


Wikipedia HERE

 


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