Alonzo Church (June 14, 1903 – August 11, 1995) was an American mathematician and logician who was responsible for some of the foundations of theoretical computer science. Born in Washington, DC, he received a bachelor's degree from Princeton University in 1924 and a Ph.D. in 1927. His advisor was Oswald Veblen. He became a professor of mathematics at Princeton in 1929.

He is best known for the development of the lambda calculus in his famous 1936 paper showing the existence of an "undecidable problem". This result preempted Alan Turing's famous work on the halting problem which also demonstrated the existence of a problem unsolvable by mechanical means. He and Turing then showed that the lambda calculus and the Turing machine used in Turing's halting problem were equivalent in capabilities, and subsequently demonstrated a variety of alternative "mechanical processes for computation" had equivalent computational abilities. This resulted in the Church-Turing thesis. As there is dispute about who proposed it first, it is also known as Church's Thesis and Turing's Thesis.

Church's other doctoral students included Stephen Kleene, J. Barkley Rosser, Leon Henkin, John George Kemeny, Michael O. Rabin, Dana Scott, Simon Kochen , Raymond Smullyan, and others (see [1]).

Church remained a professor of mathematics at Princeton until 1967, when he moved to California.

Church's lambda calculus influenced the design of the Lisp family of computer languages as well as functional programming languages in general.

See also

• Church-Turing-Deutsch principle

Books

Alonzo Church, Introduction to Mathematical Logic (ISBN 0-691-02906-7)

Sources and external links

• Church biography
• H B Enderton, In memoriam: Alonzo Church
• Church's students