member( X, [ X | T ] ).
member( X, [ _ | T ] ) :-
member( X, T ).
subset([], _).
subset([H|T], [H2|T2]) :-
member(H, [H2|T2]),
subset(T, [H2|T2]).
subset([],V).
subset([H|T1],[H|T2]) :-
subset(T1,T2).
subset([H1|T1],[H2|T2]) :-
subset([H1|T1],T2).