David Rees (mathematician)

For other persons named David/Dai Rees, see David/Dai Rees
David Rees ScD Cantab, FIMA, FRS (29 May 1918 – 16 August 2013) was an emeritus professor of pure mathematics at the University of Exeter, having been head of the Mathematics / Mathematical Sciences Department at Exeter for many years. During the Second World War, Rees was active on Enigma research in Hut 6 at Bletchley Park.

Rees was born in Abergavenny. He won a scholarship to Downing College, Cambridge. At some stage, his university career took a backseat as he was drafted into Hut 6, Bletchley Park for the war effort.

On completion of his education, he initially worked on semigroup theory, and Rees factor semigroup is named after him. He also gave a characterization of completely simple and completely 0-simple semigroups, nowadays known as Rees's theorem. The matrix-based semigroups used in this characterization are called Rees matrix semigroups. At the behest of Douglas Northcott he switched his research focus to commutative algebra. In 1954, in a joint paper with Northcott, Rees introduced the Northcott-Rees theory of reductions and integral closures which has subsequently been influential in commutative algebra. In 1956 he introduced the Rees decomposition of a commutative algebra.

Before 1960, Rees and his family moved to the University of Exeter, where their fourth child was born.

Before 1971, Rees was appointed head of the Mathematics Department at the University of Exeter.

In 1993 Rees was awarded the Pólya Prize by the London Mathematical Society. In August 1998 a conference on Commutative Algebra was held at Exeter in honour of David Rees' 80th Year. He was an Honorary Fellow of Downing College, Cambridge He was elected a Fellow of the Royal Society (FRS) in 1968.

In 1952, he married Joan S. Cushen, who became a Senior Lecturer in Mathematics at Exeter, with four children:

1. (Susan) Mary Rees FRS, Professor of Mathematics at the University of Liverpool, b. 1953
2. Rebecca Rees, b. 1955
3. Sarah E. Rees, Professor of Pure Mathematics at Newcastle University, b. 1957
4. Deborah Rees, b. 1960

• GRO Register of Marriages: JUN 1952 4a 395 CAMBRIDGE - David Rees = Joan S. Cushen
• GRO Register of Births: SEP 1953 4a 294 CAMBRIDGE - Susan M. Rees, mmn = Cushen
• Asthana, Anushka. "Academics - Times Online". The Times. London. 
• Professor Mary Rees FRS
• GRO Register of Births: DEC 1955 4a 222 CAMBRIDGE - Rebecca Rees, mmn = Cushen
• GRO Register of Births: DEC 1957 4a 338 CAMBRIDGE - Sarah E. Rees, mmn = Cushen
• Prof. Sarah Rees
• GRO Register of Births: JUN 1960 7a 442 EXETER - Deborah Rees, mmn = Cushen