Many people are walking along side an old steam engine.
A single man climbs aboard a steam engine.
There are either many or a single one. One is either walking along side or one climbs aboard.
exists e1 s1 x1 x2 x3 x4.(along(e1,x4) & n_side(x4) & Theme(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_engine(x2) & of(x2,x3) & n_steam(x3) & a_old(s1) & Theme(s1,x2) & n_people(x1) & n_quantity(x1))
exists e1 s1 x1 x2 x3.(aboard(e1,x2) & n_engine(x2) & of(x2,x3) & n_steam(x3) & Actor(e1,x1) & v_climb(e1) & n_man(x1) & a_single(s1) & Theme(s1,x1))