A person on a bmx bike.
Someone carrying a bicycle.
One cannot be on a bike while carrying that same bicycle.
exists x1 x2 x3.(a_topic(x1) & on(x1,x2) & n_bike(x2) & of(x2,x3) & n_bmx(x3) & n_person(x1))
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_carry(e1) & n_bicycle(x3) & (x1 = x2) & n_person(x1))