Program calculate Ackermann's function
Source: The Art of Prolog
Program source code: ackermann.pl
/* ackermann(X,Y,A) :- A is the value of Ackermann's function for the natural numbers X and Y. */ ackermann(0,N,s(N)). ackermann(s(M),0,Val) :- ackermann(M,s(0),Val). ackermann(s(M),s(N),Val) :- ackermann(s(M),N,Val1), ackermann(M,Val1,Val). % Program 3.9: Ackermann's function