J. Barkley Rosser

John Barkley Rosser Sr. (6 December 1907 to 5 September 1989) was an American logician and a student of Alonzo Church, known for his part in the Church-Rosser theorem in lambda calculus. He also developed what is now called the Rosser sieve in number theory. He was part of the mathematics department at Cornell University from 1936 to 1963, chairing it several times, and was later director of the Army Mathematics Research Center at the University of Wisconsin-Madison and the first director of the Communications Research Division of IDA. In 1936 he proved Rosser's trick, a stronger version of Gödel's first incompleteness theorem, and in prime number theory he proved Rosser's theorem. He also authored mathematical textbooks.