The dog returns with the hunter's bird.
The cat returns with the hunter's bird.
The bird is being brought back by either a dog or a cat.
exists x1 x2 x3 x4.(n_bird(x4) & of(x4,x3) & n_hunter(x3) & n_return(x1) & of(x1,x2) & n_dog(x2) & a_topic(x1) & with(x1,x4))
exists x1 x2 x3 x4.(n_bird(x4) & of(x4,x3) & n_hunter(x3) & n_return(x1) & of(x1,x2) & n_cat(x2) & a_topic(x1) & with(x1,x4))