% un possibile grafo aciclico

myGraph(g,h).
myGraph(g,d).
myGraph(e,d).
myGraph(h,f).
myGraph(e,f).
myGraph(a,e).
myGraph(a,b).
myGraph(b,f).
myGraph(b,c).
myGraph(f,c).

% il programma

path(X,X,[X]).
path(X,Y,[X|P]) :- myGraph(X,Z), path(Z,Y,P).