Several people are sitting on wall.
The wall is attached to a building.
Either there are several people on the wall or there are none.
exists e1 s1 x1 x2.(on(e1,x2) & n_wall(x2) & Actor(e1,x1) & v_sit(e1) & n_people(x1) & a_several(s1) & Theme(s1,x1))
exists e1 x1 x2.(n_wall(x1) & to(e1,x2) & n_building(x2) & Theme(e1,x1) & v_attach(e1))