A Basis for a Mathematical Theory of
Computation was presented in 1961 at the Western Joint Computer
Conference and in 1962 at a symposium sponsored by IBM in
Blaricum, Netherlands. Among other things, it includes a systematic theory of
conditional expressions, a treatment of their recursive use and
the method of recursion induction for proving properties of recursively
defined functions. It was published in 1963 in Computer Programming
and Formal Systems, edited by by P. Braffort and D. Hirschberg
and published by North-Holland.