Two people are on top of a cannon.
Two people are on a cannon.
People need to be on a cannon to be on top of it.
exists p1 x1.(exists x2 x3.(on(x1,x2) & of(x2,x3) & n_cannon(x3) & n_top(x2)) & n_people(x1) & card_eq_2(x1))
exists p1 x1.(exists x2.(on(x1,x2) & n_cannon(x2)) & n_people(x1) & card_eq_2(x1))