Two dogs chasing a plastic bag.
Two cats fight.
Dogs and cats are not the same species. Fighting is not the same as chasing something.
exists e1 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_chase(e1) & n_bag(x3) & of(x3,x4) & n_plastic(x4) & (x1 = x2) & n_dog(x1) & card_eq_2(x1))
exists s1 x1 x2.(n_fight(x1) & of(x1,x2) & n_cat(x2) & a_.(s1) & Theme(s1,x1) & card_eq_2(x1) & a_topic(x1))