City workers are doing maintenance on a train track.
Workers are removing old rails and installing new ones.
Maintenance doesn't mean removing old rails or installing new ones.
exists e1 x1 x2 x3 x4 x5.(on(e1,x4) & n_track(x4) & of(x4,x5) & n_train(x5) & Theme(e1,x3) & Actor(e1,x1) & v_do(e1) & n_maintenance(x3) & n_worker(x1) & (x1 = x2) & ne_geo_city(x2))
exists e1 e2 s1 s2 x1 x2 x3 x4.(Theme(e2,x4) & Actor(e2,x3) & v_install(e2) & n_one(x4) & a_new(s2) & Theme(s2,x4) & n_worker(x3) & Theme(e1,x2) & Actor(e1,x1) & v_remove(e1) & n_rail(x2) & a_old(s1) & Theme(s1,x2) & n_worker(x1))