Natural number in SWI-prolog & recursive procedure

问题

I have the next procedure for natural number is SWI-prolog:

natural_number(0).
natural_number(s(X)) :- natural_number(X).

Now I want to do a recursive call, that stop when we arrive to 0.

My natural number is represented by - s(0)=0, s(s(0))=1, s(s(s(0)))=2, etc

So I define:

recommend(A, B, natural_number(0)) :-
    dosomeFINITEfunction (a,b).
recommend(a,b,mynumber):-
    dosomeFINITEfunction(a,b),
    recommend (a,b, natural_number(mynumber)).

and call with: 3,5,s(0). But it gives me the error: out of local stack.

What is the problem? Thank you.

回答1:

natural_number(s(0), 0).
natural_number(s(s(X)), N) :- natural_number(s(X), S), N is S + 1.

来源：https://stackoverflow.com/questions/6237162/natural-number-in-swi-prolog-recursive-procedure