What I basically want to achieve is, that given a list of lists A, I want a predicate that checks if the elements of a list B are exactly contained in list A.
So for example:
A = [[1,2],[3,4],[5],[]] B = [1,2,3,4,5]
and
A = [[1,2],[3,4],[5],[]] B = [2,5,3,4,1]
Would result to true, but
A = [[1,2],[3,4],[5],[]] B = [1,2,3,4]
and
A = [[1,2],[3,4],[5],[]] B = [1,2,3,4,5,6]
would both result to false.
is this possible in prolog?
Exactly means: Order doesn't matter, it just has to contain all the elements. Also, imagine that the B list doesn't contain duplicates. So if A would contain duplicates, we should get false as a result.
The trivial answer:
?- flatten([[1,2],[3,4],[5],[]], [1,2,3,4,5]).
true.
?- flatten([[1,2],[3,4],[5],[]], [1,2,3,4]).
false.
?- flatten([[1,2],[3,4],[5],[]], [1,2,3,4,5,6]).
false.
Or,
foo(A, B) :- % because I don't know how to call it
flatten(A, B).
If you are talking about sets:
bar(A, B) :-
flatten(A, A_flat),
sort(A_flat, A_sorted),
sort(B, A_sorted).
You can use msort/2 if you don't want to remove duplicates.
If the question is, "how do I implement flatten/2", you can find several answers on SO.