The Two girls pet the small young Horse.
The girls are riding the horse.
Girls cannot be riding horse and petting horse at same time.
exists s1 s2 s3 x1 x2 x3.(n_horse(x3) & a_young(s2) & Theme(s2,x3) & a_small(s1) & Theme(s1,x3) & n_girl(x1) & card_eq_2(x1) & a_topic(x1) & Theme(s3,x3) & Actor(s3,x2) & a_pet(s3) & (x1 = x2))
exists e1 x1 x2.(n_horse(x2) & n_girl(x1) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1))