This man is riding a dirt bike on a dirt track.
A man is riding a dirt bike.
riding a dirt bike on a dirt track shows that riding a dirt bike.
exists e1 x1 x2 x3 x4 x5.(n_man(x1) & on(e1,x4) & n_track(x4) & of(x4,x5) & n_dirt(x5) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & of(x2,x3) & n_dirt(x3))
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & of(x2,x3) & n_dirt(x3) & n_man(x1))