People are checking out CDs on an counter.
Nobody is browsing at the counter.
It can either be nobody or people.
exists e1 s1 x1 x2 x3.(on(e1,x3) & n_counter(x3) & a_out(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_check(e1) & n_cd(x2) & n_people(x1))
exists x2.(n_counter(x2) & -exists e1 x1.(at(e1,x2) & Actor(e1,x1) & v_browse(e1) & n_person(x1)))