The people are walking by the train tracks.
The people are running across the tracks to beat the nearby train.
One cannot be walking by and running across simultaneously.
exists e1 x1 x2 x3.(n_track(x2) & of(x2,x3) & n_train(x3) & n_people(x1) & by(e1,x2) & Actor(e1,x1) & v_walk(e1))
exists e1 p1 s1 x1 x2 x3.(n_train(x3) & a_nearby(s1) & Theme(s1,x3) & n_track(x2) & n_people(x1) & Topic(e1,p1) & exists e2.(Theme(e2,x3) & Actor(e2,x1) & v_beat(e2)) & across(e1,x2) & Actor(e1,x1) & v_run(e1))