Работа со списком - Prolog (227193)

DOMAINS
edgelist=edge*
edge=edge(symbol,symbol)
symbollist=symbol*
 
PREDICATES
path(symbol,symbol,edgelist,symbollist)
path_aux(symbol,symbollist,edgelist,symbollist)
connect(symbol,symbol,edgelist)
belong_s(symbol,symbollist)
belong_e(edge,edgelist)
start
 
CLAUSES
 
start:-path(a,d,[edge(a,b),edge(b,c),edge(c,d),edge(b,d),edge(v,d),edge(a,v)],Path),write(Path),nl,fail.
start.
 
path(Begin,End,Graph,Path):-path_aux(Begin,[End],Graph,Path).
path_aux(Begin,[Begin|Tail_Path],_,[Begin|Tail_Path]):-!.
path_aux(Begin,[Head_Path|Tail_Path],Graph,Path):-
                            connect(Tmp,Head_Path,Graph),
                            not(belong_s(Tmp,Tail_Path)),
                            path_aux(Begin,[Tmp,Head_Path|Tail_Path],Graph,Path).
                            
connect(Node1,Node2,Graph):-belong_e(edge(Node1,Node2),Graph).
connect(Node1,Node2,Graph):-belong_e(edge(Node2,Node1),Graph).
 
belong_s(N,[N|_]).
belong_s(N,[_|T]):-belong_s(N,T).
 
belong_e(N,[N|_]).
belong_e(N,[_|T]):-belong_e(N,T).
 
GOAL
start.

["a","b","c","d"]
["a","b","d"]
["a","v","d"]