member(X,[Y|Xs]) :- member(X,Xs).
member(X,[X|Xs]).


subset([X|Xs],Ys) :- member(X,Ys), subset(Xs,Ys).
subset([],Ys).

:- subset(o,i).

/*TWDESC

The subset/2 relation

*/

/*TWDEMO

selected_norms([listlength]).

*/