A dog in a field with a Frisbee.
A cat in a field with a Frisbee.
One cannot be both a dog and a cat simultaneously.
exists x1 x2 x3.(a_topic(x1) & with(x1,x3) & n_frisbee(x3) & in(x1,x2) & n_field(x2) & n_dog(x1))
exists x1 x2 x3.(a_topic(x1) & with(x1,x3) & n_frisbee(x3) & in(x1,x2) & n_field(x2) & n_cat(x1))