The girl is sitting on a swing.
The girl is playing on the slide.
The girl cannot be playing on the slide while she is sitting on a swing.
exists e1 x1 x2.(n_girl(x1) & on(e1,x2) & n_swing(x2) & Actor(e1,x1) & v_sit(e1))
exists e1 x1 x2.(n_slide(x2) & n_girl(x1) & on(e1,x2) & Actor(e1,x1) & v_play(e1))