Alonzo Church

Alonzo Church

An American logician who created the lambda calculus in the 1930s, a minimal formal system in which everything is a function, and who proved in 1936, independently of and shortly before Turing, that the Entscheidungsproblem has no general solution. The Church–Turing thesis, which holds that anything effectively calculable is computable by these equivalent means, is named for the two of them; Turing was his doctoral student at Princeton. The lambda calculus became the theoretical basis of functional programming and shaped the design of Lisp, the language of symbolic AI. (See also: Alan Turing, John McCarthy, Symbolic AI)