Alonzo Church (nonfiction)

Alonzo Church.

Alonzo Church (June 14, 1903 – August 11, 1995) was an American mathematician and logician who made major contributions to mathematical logic and the foundations of theoretical computer science. He is best known for the lambda calculus, Church–Turing thesis, proving the undecidability of the Entscheidungsproblem, Frege–Church ontology, and the Church–Rosser theorem.

Church attended Princeton University where he was an exceptional student, publishing his first paper, on Lorentz transformations, and graduating in 1924 with a degree in mathematics. He stayed at Princeton, earning a Ph.D. in mathematics in three years under Oswald Veblen.

He married Mary Julia Kuczinski in 1925 and the couple had three children, Alonzo Church, Jr. (1929), Mary Ann (1933) and Mildred (1938).

Church made important contributions to mathematics and logic, including:

• His lambda calculus.
• His proof that the Entscheidungsproblem, which asks for a decision procedure to determine the truth of arbitrary propositions in a first-order mathematical theory, is undecidable. This is known as Church's theorem.
• His proof that Peano arithmetic is undecidable.
• His articulation of what has come to be known as the Church–Turing thesis.

He was the founding editor of the Journal of Symbolic Logic, editing its reviews section until 1979.

The lambda calculus emerged in his 1936 paper showing the unsolvability of the Entscheidungsproblem. This result preceded Alan Turing's work on the halting problem, which also demonstrated the existence of a problem unsolvable by mechanical means. Church 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." This resulted in the Church–Turing thesis.

The efforts for automatically generating a controller implementation from specifications originates from his ideas.

The lambda calculus influenced the design of the LISP programming language and functional programming languages in general.

The Church encoding is named in his honor.

Many of Church's doctoral students have led distinguished careers, including C. Anthony Anderson, Peter B. Andrews, George A. Barnard, David Berlinski, William W. Boone, Martin Davis, Alfred L. Foster, Leon Henkin, John G. Kemeny, Stephen C. Kleene, Simon B. Kochen, Maurice L'Abbé, Isaac Malitz, Gary R. Mar, Michael O. Rabin, Nicholas Rescher, Hartley Rogers, Jr., J. Barkley Rosser, Dana Scott, Raymond Smullyan, and [[Alan Turing.

He also worked on philosophy of language (see e. g. Church 1970).

Fiction cross-reference

• Crimes against mathematical constants

Nonfiction cross-reference

• Alan Turing (nonfiction)
• Alfred Foster (nonfiction) - Doctoral student
• George Alfred Barnard (nonfiction) - Doctoral student
• Goldbach's conjecture (nonfiction)
• J. Barkley Rosser (nonfiction) - Doctoral student - Rosser's trick (nonfiction)
• John G. Kemeny (nonfiction) - Doctoral student
• Lambda calculus (nonfiction)
• Leon Henkin (nonfiction) - Doctoral student
• Mathematician (nonfiction)
• Oswald Veblen (nonfiction) - Doctoral advisor
• Raymond Smullyan (nonfiction) - Doctoral student
• Stephen Cole Kleene (nonfiction) - Doctoral student

External links:

• Alonzo Church @ Wikipedia