a girl sits on a swing ride.
A girl has fallen down.
Someone who's fallen down can't also be the one who sits.
exists e1 x1 x2 x3.(on(e1,x2) & n_ride(x2) & of(x2,x3) & n_swing(x3) & Actor(e1,x1) & v_sit(e1) & n_girl(x1))
exists e1 s1 x1.(a_down(s1) & Manner(e1,s1) & Actor(e1,x1) & v_fall(e1) & n_girl(x1))