by C. Ambrose Rogers

© Oxford University Press 2004 All rights reserved

**Rado, Richard** (1906-1989), mathematician, was born on 28 April 1906 in Berlin, the second son of Leopold Rado from Budapest. He studied at the University of Berlin, and also spent some time in Göttingen. He took a DPh at Berlin with a thesis described as a 'mathematical jewel' *(Jahresbericht,* 128), under Issai Schur in 1933. On 16 March 1933 he married Luise Zadek, the elder daughter of Hermann Zadek, whom he had earlier come to know when he needed a partner to play piano duets. Their only son, Peter, was born in 1943.

As Hitler came to power in 1933, the Rados made their way to England. The decree on the civil service, issued soon after the National Socialists took power, made it impossible for those classified as Jewish to pursue academic careers in Germany, and Rado was interviewed at Berlin by Lindemann (Lord Cherwell) with a view to finding a place in England. On Lindemann's recommendation he was granted a scholarship of £300 per annum (by the chemist and philanthropist Sir Robert Mond) to enable him to study at Cambridge. He entered Fitzwilliam House in the same year and studied for a PhD under G. H. Hardy. During his stay at Cambridge he was closely associated with Harold Davenport and Hans Heilbronn, among others, and first met his later collaborator, Paul Erdoýs. After gaining his PhD in 1935 Rado was a temporary lecturer in Cambridge until 1936 when he was appointed assistant lecturer (and later lecturer) at the University of Sheffield. Among the refugee scientists living in Britain during the thirties, Rado's path to success was unusually straightforward, and he may have been assisted by the fact that he emigrated right at the beginning of his career. By 1939 he was able to assist his teacher, Issai Schur, to emigrate from Germany to Palestine.

After the war, in 1947, Rado was appointed to a readership at King's College, London, and in 1954 he became professor of mathematics at Reading, where he stayed until his retirement in 1971. He was active in the London Mathematical Society, which he served for a time as president, and he founded the British Combinatorial Committee, which he chaired until 1987. He was elected a fellow of the Royal Society in 1978. In 1981 he went to the Free University of Berlin to deliver lectures and to receive an honorary doctorate; this was described as perhaps 'the most moving experience of his life' *(The Times,* 2 Jan 1990). He was an extremely methodical person and was in the habit of making verbatim shorthand notes of lectures, seminars, and even senate meetings; his sixty-four extant diaries are likewise written in shorthand.

Rado had very wide mathematical interests and published 121 mathematical papers on an exceptionally varied range of topics. His main contribution was the development with Paul Erdoýs of the 'partition calculus'. A trivial example is the remark that if six people meet by chance, one can be sure that either at least three all know each other or there are at least three with no two knowing each other. A remarkable example (due to B. L. van der Waerden) shows that if *k* and *l* are given positive integers, then there is a large integer N, depending only on *k* and l, such that, if the numbers 1, 2, ..., *N* are split up to form *k* sequences then at least one of the sequences contains an arithmetic progression of length l. Rado and Erdoýs, with some help from others, developed these and a few other isolated examples into a coherent theory, a partition calculus, with an amazing variety of applications in mathematics and mathematical logic. Rado was fascinated by mathematical beauty and sought after it. He always tried to formulate his results at their natural level of generality, so that their full power was exhibited, without their content being obscured by over-elaboration. His work with Erdoýs and others on partition relations is described in Erdoýs, Hajnal, Maté, and Rado, *Combinatorial Set Theory: Partition Relations for Cardinals* (1984).

Rado and his wife had a double partnership: she went with him to mathematical conferences and meetings and kept contact with his mathematical friends, he was an accomplished pianist and she was a singer of professional standard. They gave many recitals both public and private, often having musical evenings in their home in Reading. Rado was the kindest and gentlest of men. He died suddenly at the Thamesfield Nursing Home, Wargrave Road, Henley-on-Thames, on 23 December 1989, and his wife died a few months later (2 June 1990). Rado was cremated at Reading on 29 December 1989.

C. AMBROSE ROGERS

**Sources **

C. A. Rogers, *Memoirs FRS,* 37 (1991), 412-26

C. Richards, ed., 'Presentation ceremony to Professor Richard Rado, at the University of Reading, May 7, 1971', *Bulletin of the Institute of Mathematics and its Applications,* 7 (1971), 237-40

P. Erdoýs, 'My joint work with Richard Rado', *Surveys in combinatorics,* ed. C. Whitehead (1987), 53-80

H. Lenz, M. Aigner, and W. Deuber, *Jahresbericht der Deutschen Mathematiker-Vereinigung,* 93 (1991), 127-45

personal knowledge (2004)

private information (2004)

P. Harper and T. E. Powell, *Catalogue of the papers and correspondence of Richard Rado* (1994)

**Archives **

U. Reading L., corresp. and papers

University of Bath, National Cataloguing Unit for the Archives of Contemporary Scientists, catalogue of MSS and corresp. | Trinity Cam., corresp. with Harold Davenport

**Likenesses **

G. Argent, photograph, 1978, RS *[see illus.]*

photograph, repro. in Lenz, Aigner, and Deuber, *Jahresbericht der Deutschen Mathematiker-Vereinigung,* 128

**Wealth at death **

£137,124: probate, 1990, *CGPLA Eng. & Wales*

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