OBITUARY : Professor David Rees

20 Aug 2013

OBITUARY : Professor David Rees
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Professor David Rees, who has died aged 95, was a pure mathematician who 
made significant contributions in fields known as semigroup theory and 
commutative algebra; during the Second World War he worked at Bletchley 
Park where, by some accounts, he made what was arguably the most important 
break into the German Enigma machine cipher.

One of the brightest mathematicians of his generation at Cambridge, Rees 
had begun postgraduate research in September 1939, when his undergraduate 
director of studies at Sidney Sussex College, Gordon Welchman, was 
recruited to work at Bletchley.

Welchman set up Hut 6, the section breaking German army and air force 
Enigma ciphers, and recruited a number of promising Cambridge 
mathematicians to work with him. They included Rees, who was immediately 
put to work in the Hut 6 Machine Room, the subsection where the Enigma 
ciphers were being broken.

Several ciphers had been broken at the beginning of 1940 as a result of 
information supplied by the Polish codebreakers. But by the spring of that 
year the Polish methods were no longer working, and Bletchley had been 
unable to make more than the occasional break into the German ciphers. The 
?Yellow? Enigma cipher used by the Germans in Norway had been relatively 
easy to crack, but the ciphers used elsewhere were proving 
difficult...../snip/


....Elected a Fellow of the Royal Society in 1968, Rees served as a member 
of its council from 1979 to 1981. In 1993 he won the Polya Prize of the 
London Mathematical Society.

In August 1998, to mark his 80th birthday, a conference on Commutative 
Algebra was held at Exeter.

In 1952 he married Joan Cushen, who, as Dr Joan Rees, would become a 
Senior Lecturer in Mathematics at Exeter. They had four daughters, of whom 
two are Mathematics professors at British universities.

Professor David Rees, born May 29 1918, died August 16 2013


http://www.telegraph.co.uk/news/obituaries/10255561/Professor-David-Rees.html

http://i.telegraph.co.uk/multimedia/archive/02648/rees_2648574b.jpg