Адаптировать метод поиска в глубину для VP7 - Prolog

domains
i=integer
s=symbol
list=s*
database
db_path(s,s,list,i)
predicates
path(s,s,list,i)
path1(s,list,i,list,i)
member(s,list)
arca(s,s,i)
db0(s,s)
db(s,s)
run(s,s)
start
goal
start.
clauses
start:-makewindow(1,7,7,"Expert System",1,3,22,71),clearwindow,
write("Enter the name of cities"),nl,
write("The first city: "), readln(First),nl,
write("The second city: "), readln(Second),nl,
run(First,Second),readchar(_).
arca (a,b,1). 
arca(a,c,1).
arca(b,e,1). 
arca(b,d,1).
arca(c,d,1).
arca(c,g,1).
arca(c,f,1).
arca(d,e,1).
arca(e,f,1).
arca(f,x,1).
run(Start,End):-db0(Start,End), db(Start,End), db_path(Start,End,MP,MD),
write("Optimum way: "),write(MP),nl,
write("Length of an optimum way="),write(MD),
nl,nl.
path(A,Z,Path,C):- path1(A,[Z],0,Path,C).
path1(A,[A|Path1],C,[A|Path1],C).
path1(A,[Y|Path1],C1,Path,C):- arca(X,Y,CXY), not(member(X,Path1)),C2=C1+CXY, path1(A,[X,Y|Path1],C2,Path,C).
member(Head,[Head|_]).
member(Head,[_|Tail]):- member(Head,Tail).
db0(X,Y) :-path(X,Y,P,C), assert(db_path(X,Y,P,C)).
db(X,Y):-db_path(X,Y,P,C), path(X,Y,MP,MC), MC<C,!,
retract(db_path(X,Y,P,C)), assert(db_path(X,Y,MP,MC)), db(X,Y).
db(_,_).

implement main
    open core
domains
i=integer.
s=symbol.
list=s*.
facts
db_path:(s,s,list,i).
class predicates
path:(s,s,list,i).
path1:(s,list,i,list,i).
member:(s,list).
arca:(s,s,i).
db0:(s,s).
db:(s,s).
start:(s,s).
run:().
clauses
run():-console::init(),stdio::write("Enter the name of cities"),console::nl,
console::write("The first city: "),console::readln(First),console::nl,
console::write("The second city: "),console::readln(Second),console::nl,
start(First,Second),console::readchar(_).
 
arca ("a","b",1).
arca("a","c",1).
arca("b","e",1).
arca("b","d",1).
arca("c","d",1).
arca("c","g",1).
arca("c","f",1).
arca("d","e",1).
arca("e","f",1).
arca("f","x",1).
 
start(Start,End):-db0(Start,End), db(Start,End), db_path(Start,End,MP,MD),
console::write("Optimum way: "),console::write(MP),console::nl,
console::write("Length of an optimum way="),console::write(MD),
console::nl,console::nl.
 
path(A,Z,Path,C):- path1(A,[Z],0,Path,C).
path1(A,[A|Path1],C,[A|Path1],C).
path1(A,[Y|Path1],C1,Path,C):- arca(X,Y,CXY), not(member(X,Path1)),C2=C1+CXY, path1(A,[X,Y|Path1],C2,Path,C).
 
member(Head,[Head|_]).
member(Head,[_|Tail]):- member(Head,Tail).
 
db0(X,Y) :-path(X,Y,P,C), assert(db_path(X,Y,P,C)).
db(X,Y):-db_path(X,Y,P,C), path(X,Y,MP,MC), MC<C,!,
retract(db_path(X,Y,P,C)), assert(db_path(X,Y,MP,MC)), db(X,Y).
db(_,_).
end implement main
goal
    console::runUtf8(main::run).