The horse on the left has white markings.
The horse has a white mane.
White markings does not necessarily mean white mane.
exists e1 s1 x1 x2 x3.(n_left(x2) & n_horse(x1) & Theme(e1,x3) & Actor(e1,x1) & v_have(e1) & n_marking(x3) & a_white(s1) & Theme(s1,x3) & on(x1,x2))
exists e1 s1 x1 x2.(n_horse(x1) & Theme(e1,x2) & Actor(e1,x1) & v_have(e1) & n_mane(x2) & a_white(s1) & Theme(s1,x2))