爲什麼'Q'在這個PROLOG程序中不統一

Question

我正在編寫一個PROLOG程序，其中感興趣的變量（Q）拒絕統一。我用一個hacky解決方案解決了這個問題（包括一個write聲明）。但是必須有一種方法來使這種統一，但爲了我的愛，我無法弄清楚。

我非常感謝任何幫助。 在此先感謝。

這裏是我的代碼（我已標註的地方我已經排除了簡碼）

:- use_module(library(bounds)). 
:- use_module(library(lists)). 

solve([17],Q,_,_,_):- write(Q). %this is the hacky workaround 
solve(L,Q,1,3,2) :- jump(L,Q,N,1,3,2,R), solve(N,R,S,D,M), member([S|[D|[M|[]]]],[[1, 3, 2], [1, 9, 4], [2, 10, 5] this list contains 76 items - all of which are lists of length 3. I have omitted them here for the sake of brevity]). 
% there are about 75 other definitions for solve, all of which are structured exactly the same. The only difference is that the numbers in the input parameters will be different in each definition 

jump(L,Q,N,S,D,M,R):- member(S,L), not(member(D,L)), member(M,L), delete(L,S,X), delete(X,M,Y), append(Y,[D],N), append(Q,[[S,D]],R). 

cross_sol(Q) :- solve([5,9,10,11,17,24],Q,S,D,M), member([S,D,M], [ 
I have edited out this list here for the sake of brevity. It is the same list found in the definition of solve 
]). 

出於某種原因，Q不統一。請幫忙！ 謝謝！

Answer 1

cross_sol/1謂詞似乎格式錯誤。

cross_sol(Q) :- solve([5,9,10,11,17,24],[],S,D,M), member([S,D,M], [ I have edited out this list here for the sake of brevity. It is the same list found in the definition of solve ]).

變量Q是單 - 它沒有在身體的任何地方引用（除非它是已抑制的部分）。