# Alonzo Church

Alonzo Church ( born June 14, 1903 in Washington, DC; † August 11, 1995 in Hudson, Ohio ) was an American mathematician, logician and philosopher and one of the founders of theoretical computer science.

He studied at Princeton University and graduated from there with a doctoral degree. After living at the University of Chicago, the Georg- August- University of Göttingen and the University of Amsterdam, he was in 1929 in Princeton professor of mathematics.

He has become known to his mathematical- logical colleagues for his development of the lambda - calculus, to which he wrote published in a 1936 ( set of Church - Rosser ) report in which he demonstrated that there are undecidable problems (ie, the answer to a question is not mathematically calculable ). This result encouraged his students to Alan Turing to reflections on the halting problem, which is also undecidable.

Church and Turing found out then that the lambda calculus and the Turing machine are equal in expressive power and still could provide some other equivalent mechanisms for computing functions. A derived therefrom thesis for the intuitive notion of computability is known as the Church - Turing thesis.

Other well-known doctoral Church were, for example, Stephen Kleene and Michael O. Rabin. Church remained a mathematics professor at Princeton until 1967. Afterwards, he moved to the University of California, Los Angeles ( UCLA). He was professor of mathematics and philosophy.

In the field of philosophy, he is known for his defense at a high level of argumentation Platonic position in modern universals.

In 1962 he gave a plenary lecture at the International Congress of Mathematicians in Stockholm ( Logic, Arithmetic and Automata ).

## Works

- Alonzo Church, Introduction to Mathematical Logic (ISBN 978-0-691-02906-1 )
- Alonzo Church, The Calculi of Lambda - Conversion (ISBN 978-0-691-08394-0 )
- Alonzo Church, A Bibliography of Symbolic Logic, 1666-1935 (ISBN 978-0-8218-0084-3 )