... used in a paper of I.Z. Ruzsaand the author [9]. In the present context things look rather different howeverand, in the absence of anything which might be called a “grain”, we think the terminology ... result of the form (6.4).For this we need Theorem 2.1, the restriction theorem for primes. The idea of constructing a1, and the technique for constructing it, hasits origins in the notions ... N).(4.4) The rather strange formulation of the theorem reflects the fact that the constant CBis ineffective for any B 1 due to the possible existence of aSiegel zero. For more information, including...