A motorcyclist in yellow.
A motorcyclist riding his/her motorcycle.
A motorcyclist is not always riding their motorcycle.
exists x1 x2.(a_topic(x1) & in(x1,x2) & n_yellow(x2) & n_motorcyclist(x1))
exists x1 x2 x3 x4.(a_topic(x1) & n_motorcycle(x1) & of(x1,x4) & n_his/her(x4) & of(x1,x3) & n_riding(x3) & of(x1,x2) & n_motorcyclist(x2))