Runners in a big city marathon.
Runners are racing in the Chicago Marathon.
Just because runners are in a big city marathon doesn't mean it's the Chicago Marathon.
exists s1 x1 x2 x3.(a_topic(x1) & in(x1,x2) & n_marathon(x2) & of(x2,x3) & n_city(x3) & a_big(s1) & Theme(s1,x2) & n_runner(x1))
exists e1 x1 x2 x3.(ne_geo_marathon(x2) & (x2 = x3) & ne_geo_chicago(x3) & in(e1,x2) & Actor(e1,x1) & v_race(e1) & n_runner(x1))