Published online by Cambridge University Press: 12 March 2014
It has been known for some time that there is a primitive recursive permutation of the nonnegative integers whose inverse is recursive but not primitive recursive. For example one has this result apparently for the first time in Kuznecov [1] and implicitly in Kent [2] or J. Robinson [3], who shows that every singularly recursive function ƒ is representable as
where A, B, C are primitive recursive and B is a permutation.
The first author was supported by Grant No. AF-AFOSR 1321-67 and the second by NSF GP-7500.