%% this is surely the simplest possible depth first search

:- ensure_loaded(showPath).

dfs :-
  dfs(Path),
  showPath(Path).

dfs(Path) :- 
  start(S), 
  dfs(S,Path).

dfs(S,[S]) :-  goal(S).
dfs(S,[S|Rest]) :- 
  arc(S,S2), 
  dfs(S2,Rest).