1907 – 1989
J. Barkley Rosser (1907–1989) was an American mathematician and logician whose work substantially advanced mathematical logic and the foundations of mathematics. He is best known for the Church-Rosser theorem in lambda calculus and for strengthening Gödel's incompleteness results via Rosser's theorem. His contributions bridge formal logic, number theory, and the semantics of formal languages.
Proved the Church-Rosser theorem (confluence of lambda calculus reduction) with Alonzo Church
Established Rosser's theorem, a strengthening of Gödel's first incompleteness theorem using a symmetric provability predicate
Developed the Rosser sieve in analytic number theory
Authored the influential textbook Logic for Mathematicians (1953)
Extended formal investigations into self-reference and semantic paradox within logical systems