A theorem, also called the iteration theorem, that makes use of the lambda notation introduced by Church. Let denote the recursive function of variables with Gödel number (where (1) is normally omitted). Then for every and , there exists a primitive recursive function such that for all , , ..., ,
A direct application of the -- theorem is the fact that there exists a primitive recursive function such that
for all and .
The -- theorem is applied in the proof of the recursion theorem. The -- theorem is the theoretical premise for a branch of computer science known as partial evaluation.