a bmx rider launches off a quarterpipe.
A bike rider is on the quarterpipe.
A bmx rider is the same as a bike rider
exists e1 s1 x1 x2 x3.(a_off(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x1) & v_launch(e1) & n_quarterpipe(x3) & n_rider(x1) & of(x1,x2) & n_bmx(x2))
exists p1 x1 x2 x3.(n_quarterpipe(x3) & on(x1,x3) & n_rider(x1) & of(x1,x2) & n_bike(x2))