There are two Boston terriers biting at each other.
the dogs are fighting over a toy
The Boston terriers are biting at each other but they aren't necessarily fighting over a toy.
exists p1 x1 e1 x2 x3 x4.((x1 = x2) & all x5.(n_other(x5) -> at(e1,x5)) & Actor(e1,x4) & v_bite(e1) & (x2 = x4) & n_terrier(x2) & (x2 = x3) & ne_geo_boston(x3) & card_eq_2(x2))
exists e1 x1 x2.(n_dog(x1) & over(e1,x2) & n_toy(x2) & Actor(e1,x1) & v_fight(e1))