A man is riding a horse while the horse in bucking.
Man riding his personal horse
Just because a man is riding a horse while the horse in bucking does not mean it is his personal horse.
exists e1 x1 x2 x3.(in(e1,x3) & n_bucking(x3) & while(e1,x2) & n_horse(x2) & n_horse(x2) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_man(x1))
exists e1 s1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_horse(x3) & a_personal(s1) & Theme(s1,x3) & of(x3,x1) & n_male(x1) & (x1 = x2) & n_man(x1))