A black dog is chasing another black dog that's carrying a ball in its mouth.
A dog chasing another dog with a ball.
A black dog is a dog, chasing another black dog, which is also a dog. They are the same thing.
exists e1 e2 s1 s2 s3 x1 x2 x3 x4 x5.(Theme(e2,x2) & Actor(e2,x1) & v_chase(e2) & Theme(e1,x4) & Actor(e1,x3) & v_carry(e1) & in(x4,x5) & n_mouth(x5) & of(x5,x1) & n_thing(x1) & n_ball(x4) & (x2 = x3) & n_dog(x2) & a_black(s3) & Theme(s3,x2) & -(x2 = x1) & n_dog(x1) & n_dog(x1) & a_black(s2) & Theme(s2,x1) & a_black(s1) & Theme(s1,x1))
exists x1 x2 x3 x4.(a_topic(x1) & with(x1,x4) & n_ball(x4) & n_dog(x3) & rel(x1,x3) & n_chasing(x1) & of(x1,x2) & n_dog(x2))