All questions with tag [math: ackermann-function]

I have problem with an inquiry i require to make use of the function of Ackermann, I require to show that Ack (2,3) = 9. A(2,3) A(1,A(2,2)) A(1,A(1,A(2,1))) A(1,A(1,A(1,A(2,0)))) A(1,A(1,A(1,A(1,1))))) A(1,A(1,A(1,A(0,A(1,0)))))) A(1,A(1,A(1,A(0,A(0,1)))))) A(1,A(1,A(1,A(0,2)))) A(1,A(1,A(1,3))) A(1,A(1,A(0,A(1,2))) A(1,A(1,A(0,A(0,A(1,1))))) A(...

I am reading the wikipedia page on ackermann's function, http://en.wikipedia.org/wiki/Ackermann_function And I am having trouble understanding WHY ackermann's function is an example of a function which is not primitive recursive. I understand that the ackermann function terminates, and thus is a total function. So why is it not primitive recursi...