Greyhounds race on a track.
The dogs are racing at the track.
Greyhounds are dogs.
exists x1 x2 x3.(a_topic(x1) & on(x1,x3) & n_track(x3) & n_race(x1) & (x1 = x2) & ne_nam_greyhounds(x2))
exists e1 x1 x2.(n_track(x2) & n_dog(x1) & at(e1,x2) & Actor(e1,x1) & v_race(e1))