電話對話邏輯謎題{Prolog}

Question

year('1928'). 
year('1929'). 
year('1932'). 
year('1935'). 

person(gertie). 
person(herbert). 
person(miriam). 
person(wallace). 

exchange(al). 
exchange(be). 
exchange(pe). 
exchange(sl). 

solve:- year(Y1), year(Y2), year(Y3), year(Y4), 
     unique([Y1,Y2,Y3,Y4]), 

    exchange(GertEx), exchange(HerbEx), exchange(MirEx), exchange(WallEx), 
    unique([GertEx,HerbEx,MirEx,WallEx]), 

    Triples= [[gertie,Y1,GertEx], 
      [herbert,Y2,HerbEx], 
      [miriam,Y3,MirEx], 
      [wallace,Y4,WallEx]], 
    %herberts first exchange was BE 
    \+ member([herbert,be,_],Triples), 
    %neither herberts nor gerties first exchange was sl 
    \+ (
     member([herbert,sl,_],Triples); 
     member([gertie,sl,_],Triples) 
     ), 
    %the BE exchange wasnt made in 1935 
    \+ member([_,be,'1935'],Triples), 
    %neither the AL nor the BE exchanges were made in 1932 
    \+ (
     member([_,al,'1932'],Triples); 
     member([_,be,'1932'],Triples) 
     ), 
    %the PE exchange was made in 1929 
     member([_,pe,'1929'],Triples), 
    %wallace's first exchange was AL 
     member([wallace,al,_],Triples), 

     writer(gertie,Y1,GertEx), 
     writer(herbert,Y2,HerbEx), 
     writer(miriam,Y3,MirEx), 
     writer(wallace,Y4,WallEx). 

writer(X,Y,Z):- write(X), write(' made the '), write(Y), write(' exchange in '), write(Z), nl. 

unique([H | T]) :- member(H, T), !, fail. 
unique([_ | T]) :- unique(T). 
unique([_]). 

我嘗試運行它，但它返回的是一個虛假的聲明。 我從http://www.cis.upenn.edu/~matuszek/cis554-2012/Assignments/prolog-01-logic-puzzle.html那裏得到了問題，從我看到的幾乎和它的-a-tie.pl樣本一樣，除了一些使用的原子和一些涉及的邏輯之外......任何人都知道我是什麼做錯了嗎？

Answer 1

似乎有交換字段。更改三同這個

Triples= [[gertie,GertEx,Y1], 
     [herbert,HerbEx,Y2], 
     [miriam,MirEx,Y3], 
     [wallace,WallEx,Y4]], 

我得到

?- solve. 
gertie made the 1928 exchange in be 
herbert made the 1929 exchange in pe 
miriam made the 1932 exchange in sl 
wallace made the 1935 exchange in al 
true .