A group of guys on the beach.
A group of guys who are all friends are on the beach.
Not all groups of guys are friends.
exists x1 x2 x3.(n_beach(x3) & a_topic(x1) & of(x1,x2) & on(x2,x3) & n_guy(x2) & n_group(x1))
exists p1 p2 x1 x2 x3 x5.(n_beach(x5) & on(x1,x5) & of(x1,x2) & all x4.(n_friend(x4) -> (x3 = x4)) & (x2 = x3) & n_guy(x2) & n_group(x1))