A little boy in a red hat riding a horse.
A girl in a blue hat is riding a horse.
The subject is either a boy or girl, with either a red or blue hat.
exists e1 s1 s2 x1 x2 x3 x4.(a_topic(x1) & in(x1,x2) & Theme(e1,x4) & Actor(e1,x3) & v_ride(e1) & n_horse(x4) & (x2 = x3) & n_hat(x2) & a_red(s2) & Theme(s2,x2) & n_boy(x1) & a_little(s1) & Theme(s1,x1))
exists e1 s1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_horse(x3) & in(x1,x2) & n_hat(x2) & a_blue(s1) & Theme(s1,x2) & n_girl(x1))