# David Champernowne

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David Champernowne [1]

David Gawen Champernowne, (July 09, 1912 - August 19, 2000)
was an English mathematician, statistician and economist who picked a hole in John Maynard Keynes' General Theory of Employment, Interest and Money [2] and 'built a chess computer' with Alan Turing [3], a long-time friend from the time that they were undergraduates together at King's College, Cambridge.

# Champernowne constant

In 1933 David Champernowne had noticed and published a simple but new result about normal numbers, introducing the Champernowne constant formed by concatenating positive integers [4] [5] [6]. Kurt Mahler later showed it to also be transcendental [7].

C10 = 0.12345678910111213141516... [8] [9]

It seems very possible that Turing's interest in the constructive definition of real numbers was stimulated by Champernowne's work, he took up this topic with some new results, and his manuscript notes were written on the back of the typescript of his 1936 paper On computable numbers [10] [11].

# Turochamp

In 1948 Turing and Champernowne devised a chess playing program which they called Turochamp, which incorporated important methods of evaluation [12]. Champernowne later gave this description of Turochamp [13]:

```Most of our attention went to deciding which moves were to be followed up. My memory about this is infuriatingly weak, Captures had to be followed up at least to the point where no further captures was immediately possible. Check and forcing moves had to be followed further. We were particularly keen on the idea that whereas certain moves would be scorned as pointless and pursued no further others would be followed quite a long way down certain paths. In the actual experiment I suspect we were a bit slapdash about all this and must have made a number of slips since the arithmetic was extremely tedious with pencil and paper. Our general conclusion was that a computer should be fairly easy to programme to play a game of chess against a beginner and stand a fair chance of winning or least reaching a winning position.
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```Turing started to code the Turochamp for Ferranti Mark 1 computer at Manchester University  but he never competed the task.
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# Round-the-house Chess

Quote from First Law [14]:

```Turing played an important role in the development of computers in Britain. Together with his friend David Champernowne he invented "round-the-house" chess: after you move, run around the house, if you get back before your opponent's move you are entitled to a new move.
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