The snow borader is riding a rail.
a snowboarder is sitting in a chair.
Riding a rail requires standing, and a person cannot also be sitting in a chair.
exists e1 x1 x2 x3.(n_borader(x1) & of(x1,x2) & n_snow(x2) & Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_rail(x3))
exists e1 x1 x2.(in(e1,x2) & n_chair(x2) & Actor(e1,x1) & v_sit(e1) & n_snowboarder(x1))