Runners in a big city marathon.
There is a group of runners.
Runners in a big city simply means group of runners
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 p1 x1 x2 x3.((x1 = x2) & of(x2,x3) & n_runner(x3) & n_group(x2))