A wakeboarder is performing a trick on a rail.
A person walks inside the room.
The wakeboarder cannot be performing a trick on a rail and walking inside the room at the same time.
exists e1 x1 x2 x3.(on(e1,x3) & n_rail(x3) & Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_trick(x2) & n_wakeboarder(x1))
exists e1 x1 x2.(n_room(x2) & inside(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_person(x1))