A crowd of people waiting for the light.
There is no one waiting for the light.
There can not simultaneously be a crowd and no one waiting.
exists e1 x1 x2 x3 x4.(n_light(x4) & a_topic(x1) & of(x1,x2) & for(e1,x4) & Actor(e1,x3) & v_wait(e1) & (x2 = x3) & n_people(x2) & n_crowd(x1))
exists p1 x1 x4.(n_light(x4) & -exists e1 x2 x3.((x1 = x2) & for(e1,x4) & Actor(e1,x3) & v_wait(e1) & (x2 = x3) & n_one(x2)))