A group of people wait in line in front of a counter.
There is no one waiting at the counter.
There can not be no one and a group of people simultaneously.
exists e1 x1 x2 x3 x4 x5.(in(e1,x4) & of(x4,x5) & n_counter(x5) & n_front(x4) & in(e1,x3) & n_line(x3) & Actor(e1,x1) & v_wait(e1) & of(x1,x2) & n_people(x2) & n_group(x1))
exists p1 x1 x4.(n_counter(x4) & -exists e1 x2 x3.((x1 = x2) & at(e1,x4) & Actor(e1,x3) & v_wait(e1) & (x2 = x3) & n_one(x2)))