“…Let p, p', p" e Ps(P, 7) be such that p <> p', p' <> p\ Then 5.14. (ii) yields p n p' < p', p' n p" < p', hence p n p' n p" < p' according to 5 guarantees that the assumptions of Lemma 5.11 are fulfilled. Applying this lemma, one obtains p n p' n p" < P n p' < p , pnp'np ff <p'np"< pV which means that p <> p".…”