prolog - prolog 中列表的公共(public)子序列

Question

我正在尝试编写一个谓词 common(L, S)，它从列表 L 的列表中生成 S 中 L 中列表的所有公共(public)子序列。

subseq([], _).
subseq([H|S], L) :- append(_, [H|T], L), subseq(S, T).


common(L, X) :- not((
        member(A, L),
        not(subseq(X, A))
       )).

即使输入错误，它也只会给我“真实”。

例如:

common([[1,2,3,4], [2,3], [12]], X).
真的


编辑

我注意到它确实有效，但它只是没有用谓词为真的术语替换 X。

Answer 1

子字符串是后缀的非空前缀。

substring_of(Ys, Xs) :-
   Ys = [_|_],           %  a non-empty
   append(_, Zs, Xs),    %                       a suffix of Xs
   append(Ys, _, Zs).    %             prefix of 

common(Xss, Xs) :-       % Xs is a substring of each element of Xss
   maplist(substring_of(Xs), Xss).

?- common([[1,2,3,4], [2,3,4,5]], Xs).
   Xs = [2]
;  Xs = [2,3]
;  Xs = [2,3,4]
;  Xs = [3]
;  Xs = [3,4]
;  Xs = [4]
;  false.