People in the city.
The people are in a forest.
If you are in the city you are not likely to be in a forest
exists x1 x2.(n_city(x2) & a_topic(x1) & in(x1,x2) & n_people(x1))
exists p1 x1.(n_people(x1) & exists x2.(in(x1,x2) & n_forest(x2)))