J. Barkley Rosser

John Barkley Rosser Sr. was an American logician, a student of Alonzo Church, and 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. He 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. Rosser also authored mathematical textbooks.