A group of boys are playing on a beach.
The boys are looking at books.
The boys can't play on a beach and look at books at the same time.
exists e1 x1 x2 x3.(on(e1,x3) & n_beach(x3) & Actor(e1,x1) & v_play(e1) & of(x1,x2) & n_boy(x2) & n_group(x1))
exists e1 x1 x2.(n_boy(x1) & at(e1,x2) & n_book(x2) & Actor(e1,x1) & v_look(e1))