prolog - Error 1, Backtrack Stack Full

Question

im trying to write a program in prolog that determine if there is a way from place to place. these are the relations:

road(ny,florida).
road(washington,florida).
road(washington,texas).
road(vegas,california).

I want to write: there_is_way(X,Y) that determine if there is a way or not. for example:

?- road(florida,ny).
no
?-there_is_way(florida,ny).
yes

This is my code:

there_is_way(X,Y):- road(X,Y);
                        road(Y,X);
                        road(X,Z),road(Z,Y),X=Y;
                        road(X,Z),road(Y,Z),X=Y;
                        road(Z,X),road(Z,Y),X=Y;
                        road(Z,X),road(Y,Z),X=Y.
there_is_way(X,Y):-
                        road(Z,Y),there_is_way(X,Z).
there_is_way(X,Y):-
                        road(Y,Z),there_is_way(X,Z).

but unfortunately I get "Error 1, Backtrack Stack Full".

someone?

thank you

Answer 1

First, we need a symmetric definition:

:- meta_predicate symm(2, ?,  ?).

symm(P_2, A, B) :-
   call(P_2, A, B).
symm(P_2, A, B) :-
   call(P_2, B, A).

Now, using closure0/3

there_is_way(A, B) :-
   closure0(symm(road), A, B).