92 N.M. Katz: By (6.4.0), this implies that the hypergeometric equation with para- meters a, b, c has "two" mod p solutions for all sufficiently large primes p satisfying pA - 1 (N). As there are only a finite number of d's to consider (Z/NZ being finite), (6.2.6) follows. Now for the necessity. Choose a A invertible in Z/NZ. By hypothesis, for every sufficiently large prime p with pA -- 1 (N), we have either (184.108.40.206) 1-- Rp(-b)>lRp(-C)>= l-- Rp(-a) P P P or (220.127.116.11) 1 Rp(- a) > 1 Rp(- c) >I Rp(- b). P P P As there are infinitely many primes with p A--I(N), either (18.104.22.168) or (22.214.171.124) must hold for infinitely many such primes. As the roles of a and b are symmetric, we may suppose (126.96.36.199) holds infinitely often for such primes. We may then apply the limit formula (188.8.131.52) to (184.108.40.206), to obtain one of the following inequalities (220.127.116.11) l>(bA)>(cA)>(aA)>O
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