 For each "p" in "P", let "A""p" denote the set of elements of "A" divisible by "p" and extend this to let "A""d" be the intersection of the "A""p" for "p" dividing "d", when "d" is a product of distinct primes from "P".Further let "A"1 denote "A" itself.Let "z" be a positive real number and "P"("z") denote the product of the primes in "P" which are ≤ "z".