A man on a horse lassoing.
A man is lassoing a bull.
A man is lassoing a bull can't be on a horse too.
exists x1 x2 x3.(a_topic(x1) & on(x1,x2) & n_lassoing(x2) & of(x2,x3) & n_horse(x3) & n_man(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_lasso(e1) & n_bull(x2) & n_man(x1))