在Prolog中排序/获取嵌套列表中的最大成员和id？

get_max_member_id([(Member, Id)], Member, Id).
get_max_member_id([(Member, Id)|Rest], MaxMember, MaxId) :-
    get_max_member_id(Rest, RestMaxMember, RestMaxId),
    (Member > RestMaxMember -> (MaxMember = Member, MaxId = Id) ; (MaxMember = RestMaxMember, MaxId = RestMaxId)).

flatten([], []).
flatten([X|Xs], Ys) :-
    flatten(X, Y),
    flatten(Xs, Ys1),
    append(Y, Ys1, Ys).
flatten(X, [X]).

sort_nested_list(List, SortedList) :-
    flatten(List, FlatList),
    sort(FlatList, SortedFlatList),
    group_sorted_list(SortedFlatList, SortedList).

group_sorted_list([], []).
group_sorted_list([X|Xs], [[X|Group]|Rest]) :-
    group(X, Xs, Group, NewXs),
    group_sorted_list(NewXs, Rest).

group(X, [], [], []).
group(X, [Y|Ys], [], [Y|Ys]) :-
    X \= Y.
group(X, [X|Xs], [X|Group], Rest) :-
    group(X, Xs, Group, Rest).

?- List = [[(3, 1), (2, 2)], [(5, 3), (4, 4), (1, 5)], [(6, 6)]],
   sort_nested_list(List, SortedList),
   get_max_member_id(SortedList, MaxMember, MaxId).