The boys play on the rocks overlooking the valley.
The boys are playing indoors.
It is impossible for a boy to be indoors and at rocks overlooking the valley at the same time because it is impossible to be in two locations at once
exists e1 e2 x1 x2 x3.(n_valley(x3) & n_rock(x2) & n_boy(x1) & for(e1,e2) & Theme(e2,x3) & Actor(e2,x1) & v_overlook(e2) & on(e1,x2) & Actor(e1,x1) & v_play(e1))
exists e1 x1 x2.(n_boy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_indoor(x2))