They are playing ice-hockey.
They are not playing ice hockey.
either they are playing ice hockey or not
exists e1 x1 x2.(n_thing(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_ice-hockey(x2))
exists x1.(n_thing(x1) & -exists e1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_hockey(x2) & of(x2,x3) & n_ice(x3)))