Proper noun
Ackermann function
(computing theory) One of the simplest and earliest examples of a total computable function that is not primitive recursive.
All primitive recursive functions are total and computable, but the Ackermann function illustrates that not all total computable functions are primitive recursive. Source: Internet
For example, the Ackermann function can be proven to be total recursive, but not primitive. Source: Internet
Table of values Computing the Ackermann function can be restated in terms of an infinite table. Source: Internet
The Ackermann function A(m,n) is a well-known example of a total recursive function (in fact, provable total), that is not primitive recursive. Source: Internet
There is a characterization of the primitive recursive functions as a subset of the total recursive functions using the Ackermann function. Source: Internet