Police officers having a discussion.
They are in uniform.
Police officers are not always in uniform.
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_have(e1) & n_discussion(x3) & n_officer(x1) & of(x1,x2) & n_police(x2))
exists p1 x1.(n_thing(x1) & exists x2.(in(x1,x2) & n_uniform(x2)))