A person riding a gray horse who has just jumped.
a person on horse
One has to be on horse in order to be riding horse.
exists e2 e1 s1 s2 x1 x2 x3 x4.(a_topic(x1) & a_just(s2) & Manner(e2,s2) & Actor(e2,x4) & v_jump(e2) & (x1 = x4) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_horse(x3) & a_gray(s1) & Theme(s1,x3) & (x1 = x2) & n_person(x1))
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_horse(x2) & n_person(x1))