People walking in a supermarket.
There is no one here.
There cannot be no one in a supermarket if people are walking in
exists e1 x1 x2 x3.(a_topic(x1) & in(e1,x3) & n_supermarket(x3) & Actor(e1,x2) & v_walk(e1) & (x1 = x2) & n_people(x1))
exists p1 x1.-exists x2.((x1 = x2) & r_here(x2) & n_one(x2))