A group of people are rafting on river rapids.
The people are sitting on a couch.
One cannot be sitting and rafting simultaneously.
exists e1 x1 x2 x3 x4.(on(e1,x3) & n_rapid(x3) & of(x3,x4) & n_river(x4) & Actor(e1,x1) & v_raft(e1) & of(x1,x2) & n_people(x2) & n_group(x1))
exists e1 x1 x2.(n_people(x1) & on(e1,x2) & n_couch(x2) & Actor(e1,x1) & v_sit(e1))