A man is lying on the sidewalk.
A woman is lying on the sidewalk.
There can be either a man or a woman.
exists e1 x1 x2.(n_sidewalk(x2) & on(e1,x2) & Actor(e1,x1) & v_lie(e1) & n_man(x1))
exists e1 x1 x2.(n_sidewalk(x2) & on(e1,x2) & Actor(e1,x1) & v_lie(e1) & n_woman(x1))