A dirt biker aggitates dirt on a four wheeler.
A human is on a vehicle outdoors.
If there is a dirt biker, someone is on a vehicle outdoors.
exists e1 x1 x2 x3 x4.(on(e1,x4) & n_wheeler(x4) & card_eq_4(x4) & Theme(e1,x3) & Actor(e1,x1) & v_aggitate(e1) & n_dirt(x3) & n_biker(x1) & of(x1,x2) & n_dirt(x2))
exists p1 x1.(exists x2 x3.(on(x1,x2) & n_outdoors(x2) & of(x2,x3) & n_vehicle(x3)) & n_human(x1))