P(n) in Peano arithmetic grows phenomenally fast as a function of n, far faster than any primitiverecursive function(英语:primitiverecursive function) or
semantics, where the denotations of recursive programs is built up corecursively in this way. In Python, a recursive factorial function can be defined as:
Nostran Reinholds Company (1964). Frege, Gottlob. The Foundations of Arithmetic. Evanston, IL: Northwestern University Press (1980). Martin, Brian. The