Two go-cart drivers are racing on the racetrack.
Two bikes are racing on a race track.
Go-carts and bikes are not the same type of vehicle.
exists e1 s1 x1 x2.(n_racetrack(x2) & on(e1,x2) & Actor(e1,x1) & v_race(e1) & n_driver(x1) & a_go-cart(s1) & Theme(s1,x1) & card_eq_2(x1))
exists e1 x1 x2 x3.(on(e1,x2) & n_track(x2) & of(x2,x3) & n_race(x3) & Actor(e1,x1) & v_race(e1) & n_bike(x1) & card_eq_2(x1))