Lady sitting at the piano.
The lady is near the piano.
It is only possible for the lady to be sitting at the piano if the lady is near the piano.
exists e1 x1 x2.(n_piano(x2) & ne_nam_lady(x1) & at(e1,x2) & Actor(e1,x1) & v_sit(e1))
exists p1 x1 x2.(n_piano(x2) & n_lady(x1) & near(x1,x2))