Background
Alonzo Church was born on June 14, 1903, in Washington, District of Columbia, United States. He was the son of Samuel Robbins and Mildred Hannah Letterman (Parker) Church.
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1941
educator mathematician scientist
Alonzo Church was born on June 14, 1903, in Washington, District of Columbia, United States. He was the son of Samuel Robbins and Mildred Hannah Letterman (Parker) Church.
Church got Bachelor of Arts degree at Princeton University in 1924, and Doctor of Philosophy degree at Princeton University in 1927. He was an Honorary Doctor of Science at the same university, 1985.
Alonzo became an Honorary Doctor of Science in Case Western Reserve University, 1969, and an Honorary Doctor of Science in State University of New York, Buffalo, 1990.
Church taught mathematics and philosophy at Princeton from 1929 to 1967. That same year he became a professor of mathematics and philosophy at the University of California at Los Angeles and worked there until his retirement in 1990. Simultaneously he edited the Journal of Symbolic Logic from 1936 to 1979. He was the Editor of The Journal of Symbolic Logic for many years and contributed a vast array of review articles to that Journal, many of considerable interest in their own tight.
Alonzo Church was a central figure in the development of mathematical logic. He was the first to prove the undecidability of first-order logic: that is, that there is no mechanical procedure for deciding whether an arbitrary sentence in first-order logic is a theorem or not. This result is known as Church’s Theorem.
Church also formulated a statement which, while not capable of formal demonstration, is widely accepted. This is Church’s Thesis, which asserts that a number theoretic function is effectively computable if and only if that function is recursive. He thus reduced the informal concept of effective computability to the precisely defined concept of recursiveness. Church’s thesis is important because the repetition of a simple action can result in significant changes. It also means that one simple action can be useful over a broad range of problems, and at different levels of a problem.
Church's Thesis leads to the important result that there is no effective method for deciding the truth or falsity of an arbitrary sentence in elementary number theory.
He made an important contribution to the foundations of probability via his refinement of von Mises’s theory of random sequences. Church’s contributions to logic can be found in any serious textbook.
His contribution to the foundation of computer programming is that he discovered the importance of recursiveness in solving logical problems. That is, for calculations to take place, some actions (e.g. adding or subtracting) have to be repeated a certain number of times.
Church was a member of American Academy Arts and Sciences, Association Symbolic Logic, American Mathematics Society, American Association for the Advancement of Science, National Academy of Sciences and British Academy (as a correspondent).
Church’s private life is very quiet and unremarkable. As Andrew Hodges said in his biography of Alan Turing (Church’s famed student, who killed himself in 1954 after being arrested on homosexual charges), Church “[is] a retiring man himself, not given to a great deal of discussion.”
Church married Mary Julia Kuczinski on August 25, 1925. She deceased on February 1976. They had 3 children – Alonzo, Mary Anna and Mildred Warner.
