A group of people sift through shelves of books.
people going through pile of books
The books could be neatly arranged on a shelf and are not in a pile.
exists e1 x1 x2 x3 x4.(through(e1,x3) & of(x3,x4) & n_book(x4) & n_shelf(x3) & Actor(e1,x1) & v_sift(e1) & of(x1,x2) & n_people(x2) & n_group(x1))
exists e1 x1 x2 x3 x4.(a_topic(x1) & through(e1,x3) & of(x3,x4) & n_book(x4) & n_pile(x3) & Actor(e1,x2) & v_go(e1) & (x1 = x2) & n_people(x1))