Rea> a then Ll = = {w: >a}, =a= If U

LEMMA 2.2f. Let p e .J.I[a, n], with p(z) =f. a and n ~ 1. If z0 e U and

R zop''(zo) 1 > 0 e '( ) + - . p Zo

negative. Applying this to inequality (ii) leads to

(2.2-9) n 2 .