Prolog 管线任务

我有一项任务是在序言中制作一张简化的地铁地图，其中一部分要求制定一项规则来检查两个车站是否在同一条线上，我有一条规则，但它似乎不起作用，这就是我到目前为止所拥有的：

adjacent(nh,lg,central,4).
adjacent(lg,oc,central,4).
adjacent(oc,tc,central,4).
adjacent(tc,cl,central,4).
adjacent(cl,ls,central,4).
adjacent(ls,bg,central,4).
adjacent(br,vi,victoria,4).
adjacent(vi,oc,victoria,4).
adjacent(oc,ws,victoria,4).
adjacent(ws,kx,victoria,4).
adjacent(kx,fp,victoria,4).
adjacent(ke,em,northern,4).
adjacent(em,tc,northern,4).
adjacent(tc,ws,northern,4).
adjacent(ws,eu,northern,4).
adjacent(al,ls,metropolitan,4).
adjacent(ls,kx,metropolitan,4).
adjacent(kx,bs,metropolitan,4).
adjacent(bs,fr,metropolitan,4).
adjacent(ec,em,bakerloo,4).
adjacent(em,oc,bakerloo,4).
adjacent(oc,pa,bakerloo,4).
adjacent(pa,wa,bakerloo,4).

next(X,Y,L):-adjacent(X,Y,L,_).
next(X,Y,L):-adjacent(Y,X,L,_).
direct_connect(X,Y,L,S,F):-
                next(X,Z,L),
                not(member(Z,S)),
                direct_connect(Z,Y,L,[Z|S],F).
direct_connect(X,Y,L,S,[Y|S]):- next(X,Y,L).
one_change(X,Y,L,F):- 
                direct_connect(X,Z,L,[X],F1),
                direct_connect(Z,Y,L2,[Z|F1],F),
                L\=L2.
exist(X):-next(X,_,_).
member(X,[X|_]).
member(X,[_|T]):-member(X,T).
route(X,Y,F):-exist(X),exist(Y), 
              direct_connect(X,Y,_,[X],F),
              write('Direct Connection'),nl,
              revwrite(F).
route(X,Y,F):-exist(X),exist(Y), 
              one_change(X,Y,_,F), 
              write('One change required'),nl,  
              revwrite(F).
revwrite([X]):-write(X).
revwrite([H|T]):-revwrite(T), write('->'),write(H).

和规则；

sameLine(Stat1, Stat2, Line) :-
  station(Stat1, Line),
  station(Stat2, Line),
  Stat1 \= Stat2.

对于不清楚且没有发布代码的情况表示抱歉，通过电话发布：/