A man in a sweater is looking at dirty stairs.
The stairs are sparkling clean.
If the stairs are sparkling clean they cannot also be dirty.
exists e1 s1 x1 x2 x3.(at(e1,x3) & n_stair(x3) & a_dirty(s1) & Theme(s1,x3) & Actor(e1,x1) & v_look(e1) & in(x1,x2) & n_sweater(x2) & n_man(x1))
exists e1 p1 x1.(n_stair(x1) & exists s1.(Theme(s1,x1) & a_clean(s1)) & Topic(e1,p1) & Actor(e1,x1) & v_sparkle(e1))