A man teaches a classroom of children.
The classroom is empty and the janitor is cleaning it.
The classroom cannot have children and be empty.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_teach(e1) & of(x2,x3) & n_child(x3) & n_classroom(x2) & n_man(x1))
exists e1 s1 x1 x2.(n_thing(x1) & n_janitor(x2) & n_classroom(x1) & Theme(e1,x1) & Actor(e1,x2) & v_clean(e1) & Theme(s1,x1) & a_empty(s1))