# Stephen Kleene

Updated: 09/15/2017 by Computer Hope

**Name:** Stephen Kleene

**Born:** January 5, 1909, in Hartford, Connecticut USA

**Death:** January 25, 1994 (Age: 85)

## Computer-related contributions

- American mathematician who co-founded the branch of mathematical logic known as recursion theory, along with Alan Turing, Emil Post, and others.
- His worked contributed to the foundations of theoretical computer science.
- Inventor of regular expressions in mathematics.

## Significant publications

- Origins of Recursive Function Theory (1981).
- Mathematical Logic (1967).
- The Foundations of Intuitionistic Mathematics (1965).
- Representation of Events in Nerve Nets and Finite Automata (1956).
- Introduction to Metamathematics (1952).

## Honors and awards

- National Medal of Science (1990).
- Leroy P. Steele Prize (1983).
- Numerous mathematical concepts are named after him: Kleene hierarchy, Kleene algebra, the Kleene star (Kleene closure), Kleene's recursion theorem and the Kleene fixpoint theorem.

## Quotes

"I had some hesitations about philosophy because, if you worked out a philosophical theory, it was hard to know whether you were going to be able to prove it or whether other theories had just as good a claim on belief."