Kleene was initially a student under Alonzo Church where did important work on the Lambda calculus. Most notably at the University of Wisconsin he invented the regular expression, and laid the foundation of the recursion theory.
Kleene’s work on Gödel’s incompleteness theorem ensured that it was better understood by the science community and easier to teach.
- Kleene pronounced his last name /ˈkleɪniː/ KLAY-nee; /ˈkliːniː/ and /ˈkliːn/ are common mispronunciations. (His son, Ken Kleene, wrote: “As far as I am aware this pronunciation is incorrect in all known languages. I believe that this novel pronunciation was invented by my father.”)
- Although a private man, he was a skilful and enthusiastic teller of anecdotes. He possessed a powerful voice that always made it possible for others to know without seeing him whether he was in the maths building.