A man on a horse is attempting to lasso a dog.
The man is on a horse.
horse is attempting to lasso a dog implies that  man is on a horse.`
exists e1 p1 x1 x2.(Topic(e1,p1) & Actor(e1,x1) & v_attempt(e1) & exists e2 x3.(Theme(e2,x3) & Actor(e2,x1) & v_lasso(e2) & n_dog(x3)) & on(x1,x2) & n_horse(x2) & n_man(x1))
exists p1 x1.(n_man(x1) & exists x2.(on(x1,x2) & n_horse(x2)))