ROTH, KLAUS FRIEDRICH

ROTH, KLAUS FRIEDRICH (1925– ), English mathematician. Born in Breslau, Germany (now Wroclaw, Poland), Roth came to England where he was educated at St. Paul's School, London, before graduating with a B.A. in mathematics from Cambridge University (1945). After teaching at Gordonstoun School in Scotland, he joined the mathematics department of University College, London (1946–66) where he gained his M.A. (1948), Ph.D. (1950) and became professor (1961). He moved to Imperial College of Science and Technology, London as professor of pure mathematics (1966–88) and visiting professor (1988–96) before returning to Scotland. Roth's main interest is the theory of numbers. He solved the major problem of approximating algebraic numbers by rationals (his solution is now known as "Roth's theorem") and published Rational Approximations to Irrational Numbers (1962). He made other important contributions to the theory of natural numbers. His achievements have been recognized by many honors including the Fields Medal (1958), election to the Royal Society of London (1960) and the award of the Royal Society's Sylvester Medal (1991). (Michael Denman (2nd ed.)