Three dogs on a sidewalk.
The dogs are in the suburbs.
These sentences are not necessarily a contradiction because suburbs have sidewalks, typically.  It is perhaps a jump in logic to assume the sidewalk is in the suburbs.
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_sidewalk(x2) & n_dog(x1) & card_eq_3(x1))
exists p1 x1 x2.(n_suburb(x2) & n_dog(x1) & in(x1,x2))