Horseback riders file down a wooded path.
People are riding on horses.
Horseback riders must be riding horses.
exists e1 e2 s1 x1 x2 x3.(a_down(s1) & Manner(e2,s1) & Theme(e2,x3) & Actor(e2,x1) & v_file(e2) & n_path(x3) & Theme(e1,x3) & v_wood(e1) & n_rider(x1) & (x1 = x2) & ne_nam_horseback(x2))
exists e1 x1 x2.(on(e1,x2) & n_horse(x2) & Actor(e1,x1) & v_ride(e1) & n_people(x1))