Motorcycle police officer rides in a parade.
Firefighters are in a parade.
They are either firefighters or police, not both
exists x1 x2 x3 x4 x5.(a_topic(x1) & in(x1,x5) & n_parade(x5) & n_ride(x1) & of(x1,x4) & n_officer(x4) & of(x1,x3) & n_police(x3) & (x1 = x2) & ne_nam_motorcycle(x2))
exists p1 x1.(exists x2.(in(x1,x2) & n_parade(x2)) & n_firefighter(x1))