A toddler watching the pigeons across the street.
Nobody is watching
Toddler and nobody are different.
exists e1 x1 x2 x3 x4.(n_street(x4) & n_pigeon(x3) & a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_watch(e1) & across(x3,x4) & (x1 = x2) & n_toddler(x1))
-exists e1 x1.(Actor(e1,x1) & v_watch(e1) & n_person(x1))