The couple is sitting on a rock overlooking a valley.
The couple is on  date.
A couple sitting on a rock aren't necessarily on date.
exists e2 e1 x1 x2 x3 x4.(n_couple(x1) & on(e1,x2) & Theme(e2,x4) & Actor(e2,x3) & v_overlook(e2) & n_valley(x4) & (x2 = x3) & n_rock(x2) & Actor(e1,x1) & v_sit(e1))
exists p1 x1.(n_couple(x1) & exists x2.(on(x1,x2) & n_date(x2)))