The city at night.
A city under the moon
at night doesn't imply under the moon
exists x1 x2.(n_city(x1) & a_topic(x1) & at(x1,x2) & n_night(x2))
exists x1 x2.(n_moon(x2) & a_topic(x1) & under(x1,x2) & n_city(x1))