A man riding a dirt bike
Man riding bike at park
The fact that a man riding a bike doesn't imply that he is riding at park.
exists e1 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_bike(x3) & of(x3,x4) & n_dirt(x4) & (x1 = x2) & n_man(x1))
exists x1 x2 x3 x4.(a_topic(x1) & at(x1,x4) & n_park(x4) & n_bike(x1) & of(x1,x3) & n_riding(x3) & of(x1,x2) & n_man(x2))