A man jumping on his bmx with another bmxer watching.
No one is jumping on a bike.
If there is no one, there cannot be a man and another bmxer.
exists e1 x1 x2 x3 x4 x5 x6.(a_topic(x1) & with(e1,x6) & n_watching(x6) & of(x6,x5) & n_bmxer(x5) & -(x6 = x4) & n_watching(x4) & of(x4,x5) & on(e1,x3) & n_bmx(x3) & of(x3,x1) & n_male(x1) & Actor(e1,x2) & v_jump(e1) & (x1 = x2) & n_man(x1))
-exists e1 x1 x2.(on(e1,x2) & n_bike(x2) & Actor(e1,x1) & v_jump(e1) & n_one(x1))