Multiple students sitting on stairs at a school.
Teachers are gathered at the stairwell.
There are either students or teachers, not both, and they are either sitting on stairs or gathered at the stairwell, not both.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & at(e1,x5) & n_school(x5) & on(e1,x4) & n_stair(x4) & Actor(e1,x3) & v_sit(e1) & (x1 = x3) & n_student(x1) & (x1 = x2) & ne_nam_multiple(x2))
exists e1 x1 x2.(n_stairwell(x2) & at(e1,x2) & Theme(e1,x1) & v_gather(e1) & n_teacher(x1))