A child runs down an elevated walkway in a city.
A child runs in a city.
Sentence 2 simply takes out the extra details of sentence 1, "down an elevated walkway" without the sentence losing meaning.
exists e1 s1 x1 x2 x3.(down(e1,x2) & in(x2,x3) & n_city(x3) & n_walkway(x2) & a_elevated(s1) & Theme(s1,x2) & Actor(e1,x1) & v_run(e1) & n_child(x1))
exists e1 x1 x2.(in(e1,x2) & n_city(x2) & Actor(e1,x1) & v_run(e1) & n_child(x1))