a biker jumps over a pile of dirt.
The person is riding on some dirt.
When a person is riding that person is a biker.
exists e1 x1 x2 x3.(over(e1,x2) & of(x2,x3) & n_dirt(x3) & n_pile(x2) & Actor(e1,x1) & v_jump(e1) & n_biker(x1))
exists e1 x1 x2.(n_person(x1) & on(e1,x2) & n_dirt(x2) & Actor(e1,x1) & v_ride(e1))