A motorcyclist is sporting a very colorful helmet.
There is nothing on the person's head.
If one is sporting a helmet, then there cannot be nothing on their head.
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_sport(e1) & n_helmet(x2) & a_colorful(s1) & Theme(s1,x2) & r_very(x2) & n_motorcyclist(x1))
exists p1 x1 x3 x4.(n_head(x4) & of(x4,x3) & n_person(x3) & -exists x2.((x1 = x2) & on(x2,x4) & n_thing(x2)))