A lady is playing with the baby laying on the couch.
No one is on the couch
A lady and a baby are on the couch, they are not "no one."
exists e2 e1 x1 x2 x3 x4.(n_couch(x4) & n_baby(x2) & with(e1,x2) & on(e2,x4) & Actor(e2,x3) & v_lay(e2) & (x2 = x3) & Actor(e1,x1) & v_play(e1) & n_lady(x1))
exists x2.(n_couch(x2) & -exists p1 x1.(on(x1,x2) & n_one(x1)))